Non-coplanar helimagnetism in the layered van-der-Waals metal DyTe3.

Van-der-Waals magnetic materials can be exfoliated to realize ultrathin sheets or interfaces with highly controllable optical or spintronics responses. In majority, these are collinear ferro-, ferri-, or antiferromagnets, with a particular scarcity of lattice-incommensurate helimagnets of defined left- or right-handed rotation sense, or helicity. Here, we report polarized neutron scattering experiments on DyTe3, whose layered structure has highly metallic tellurium layers separated by double-slabs of dysprosium square nets. We reveal cycloidal (conical) magnetic textures, with coupled commensurate and incommensurate order parameters, and probe the evolution of this ground state in a magnetic field. The observations are well explained by a one-dimensional spin model, with an off-diagonal on-site term that is spatially modulated by DyTe3's unconventional charge density wave (CDW) order. The CDW-driven term couples to antiferromagnetism, or to the net magnetization in an applied magnetic field, and creates a complex magnetic phase diagram indicative of competing interactions in this easily cleavable van-der-Waals helimagnet.

Enhanced emergent electromagnetic inductance in Tb5Sb3 due to highly disordered helimagnetism.

In helimagnetic metals, ac current-driven spin motions can generate emergent electric fields acting on conduction electrons, leading to emergent electromagnetic induction (EEMI). Recent experiments reveal the EEMI signal generally shows a strongly current-nonlinear response. In this study, we investigate the EEMI of Tb5Sb3, a short-period helimagnet. Using small angle neutron scattering we show that Tb5Sb3 hosts highly disordered helimagnetism with a distribution of spin-helix periodicity. The current-nonlinear dynamics of the disordered spin helix in Tb5Sb3 indeed shows up as the nonlinear electrical resistivity (real part of ac resistivity), and even more clearly as a nonlinear and huge EEMI (imaginary part of ac resistivity) response. The magnitude of the EEMI reaches as large as several tens of µH for Tb5Sb3 devices on the scale of several tens of µm, originating to noncollinear spin textures possibly even without long-range helimagnetic order.

Observation by SANS and PNR of pure Néel-type domain wall profiles and skyrmion suppression below room temperature in magnetic [Pt/CoFeB/Ru]10 multilayers.

We report investigations of the magnetic textures in periodic multilayers [Pt(1 nm)/(CoFeB(0.8 nm)/Ru(1.4 nm)]10 using polarised neutron reflectometry (PNR) and small-angle neutron scattering (SANS). The multilayers are known to host skyrmions stabilized by Dzyaloshinskii-Moriya interactions induced by broken inversion symmetry and spin-orbit coupling at the asymmetric interfaces. From depth-dependent PNR measurements, we observed well-defined structural features and obtained the layer-resolved magnetization profiles. The in-plane magnetization of the CoFeB layers calculated from fitting of the PNR profiles is found to be in excellent agreement with magnetometry data. Using SANS as a bulk probe of the entire multilayer, we observe long-period magnetic stripe domains and skyrmion ensembles with full orientational disorder at room temperature. No sign of skyrmions is found below 250 K, which we suggest is due to an increase of an effective magnetic anisotropy in the CoFeB layer on cooling that suppresses skyrmion stability. Using polarised SANS at room temperature, we prove the existence of pure Néel-type windings in both stripe domain and skyrmion regimes. No Bloch-type winding admixture, i.e. an indication for hybrid windings, is detected within the measurement sensitivity, in good agreement with expectations according to our micromagnetic modelling of the multilayers. Our findings using neutron techniques provide valuable microscopic insights into the rich magnetic behavior of skyrmion-hosting multilayers, which are essential for the advancement of future skyrmion-based spintronic devices.

The study presents a unique investigation of [Pt/CoFeB/Ru]₁₀ multilayers, revealing suppressed skyrmion phases, intricate magnetic domain structures, and Néel-type domain walls, providing crucial insights for spintronic applications.

Transition between distinct hybrid skyrmion textures through their hexagonal-to-square crystal transformation in a polar magnet.

Magnetic skyrmions, topological vortex-like spin textures, garner significant interest due to their unique properties and potential applications in nanotechnology. While they typically form a hexagonal crystal with distinct internal magnetisation textures known as Bloch- or Néel-type, recent theories suggest the possibility for direct transitions between skyrmion crystals of different lattice structures and internal textures. To date however, experimental evidence for these potentially useful phenomena have remained scarce. Here, we discover the polar tetragonal magnet EuNiGe3 to host two hybrid skyrmion phases, each with distinct internal textures characterised by anisotropic combinations of Bloch- and Néel-type windings. Variation of the magnetic field drives a direct transition between the two phases, with the modification of the hybrid texture concomitant with a hexagonal-to-square skyrmion crystal transformation. We explain these observations with a theory that includes the key ingredients of momentum-resolved Ruderman-Kittel-Kasuya-Yosida and Dzyaloshinskii-Moriya interactions that compete at the observed low symmetry magnetic skyrmion crystal wavevectors. Our findings underscore the potential of polar magnets with rich interaction schemes as promising for discovering new topological magnetic phases.

Small-angle neutron scattering study of mesoscale magnetic disordering and skyrmion phase suppression in the frustrated chiral magnet Co6.75Zn6.75Mn6.5.

Co-Zn-Mn chiral cubic magnets display versatile magnetic skyrmion phases, including equilibrium phases stable far above and far below room temperature, and the facile creation of robust far-from-equilibrium skyrmion states. In this system, compositional disorder and magnetic frustration are key ingredients that have profound effects on the chiral magnetism. Reported here are studies of the magnetism in Co6.75Zn6.75Mn6.5 by magnetometry, small-angle neutron scattering (SANS), magnetic diffuse neutron scattering and Lorentz transmission electron microscopy (LTEM). While features in magnetometry and LTEM often give standard indications for skyrmion formation, they are not readily observed from the measurements on this system. Instead, skyrmion lattice correlations are only revealed by SANS, and they are found to form an orientationally disordered structure in a minority fraction of the sample. The majority fraction of the sample always displays orientationally disordered helical spin correlations, which undergo further disordering along the radial direction on cooling below the critical temperature (T c ≃ 102 K). The near-complete suppression of the skyrmion phase, and the process of disordering on cooling, are attributed to competing magnetic interactions that dominate over the ferromagnetic interaction expected to favour chiral magnetism in this system. These competing interactions start to develop above T c and become further enhanced towards low temperatures. The present observations of co-existing and disordered magnetic correlations over multiple length scales are not unique to Co6.75Zn6.75Mn6.5 but are seemingly common to the family of Co-Zn-Mn compounds with finite Mn, and their accurate description presents a challenge for theoretical modelling. In addition, this study highlights a need for neutron instrumentation capable of the comprehensive measurement of magnetic correlations over expanded ranges of momentum transfer in such multiple-length-scale magnets.

Square and rhombic lattices of magnetic skyrmions in a centrosymmetric binary compound.

Magnetic skyrmions are topologically stable swirling spin textures with particle-like character, and have been intensively studied as a candidate of high-density information bit. While magnetic skyrmions were originally discovered in noncentrosymmetric systems with Dzyaloshinskii-Moriya interaction, recently a nanometric skyrmion lattice has also been reported for centrosymmetric rare-earth compounds, such as Gd2PdSi3 and GdRu2Si2. For the latter systems, a distinct skyrmion formation mechanism mediated by itinerant electrons has been proposed, and the search of a simpler model system allowing for a better understanding of their intricate magnetic phase diagram is highly demanded. Here, we report the discovery of square and rhombic lattices of nanometric skyrmions in a centrosymmetric binary compound EuAl4, by performing small-angle neutron and resonant elastic X-ray scattering experiments. Unlike previously reported centrosymmetric skyrmion-hosting materials, EuAl4 shows multiple-step reorientation of the fundamental magnetic modulation vector as a function of magnetic field, probably reflecting a delicate balance of associated itinerant-electron-mediated interactions. The present results demonstrate that a variety of distinctive skyrmion orders can be derived even in a simple centrosymmetric binary compound, which highlights rare-earth intermetallic systems as a promising platform to realize/control the competition of multiple topological magnetic phases in a single material.

Topological Magnetic Phase in the Candidate Weyl Semimetal CeAlGe.

We report the discovery of topological magnetism in the candidate magnetic Weyl semimetal CeAlGe. Using neutron scattering we find this system to host several incommensurate, square-coordinated multi-k[over →] magnetic phases below T_{N}. The topological properties of a phase stable at intermediate magnetic fields parallel to the c axis are suggested by observation of a topological Hall effect. Our findings highlight CeAlGe as an exceptional system for exploiting the interplay between the nontrivial topologies of the magnetization in real space and Weyl nodes in momentum space.

Tomonaga-Luttinger Liquid Spin Dynamics in the Quasi-One-Dimensional Ising-Like Antiferromagnet BaCo_{2}V_{2}O_{8}.

Combining inelastic neutron scattering and numerical simulations, we study the quasi-one-dimensional Ising anisotropic quantum antiferromagnet BaCo_{2}V_{2}O_{8} in a longitudinal magnetic field. This material shows a quantum phase transition from a Néel ordered phase at zero field to a longitudinal incommensurate spin density wave at a critical magnetic field of 3.8 T. Concomitantly, the excitation gap almost closes and a fundamental reconfiguration of the spin dynamics occurs. These experimental results are well described by the universal Tomonaga-Luttinger liquid theory developed for interacting spinless fermions in one dimension. We especially observe the rise of mainly longitudinal excitations, a hallmark of the unconventional low-field regime in Ising-like quantum antiferromagnetic chains.

Oriented 3D Magnetic Biskyrmions in MnNiGa Bulk Crystals.

A biskyrmion consists of two bound, topologically stable, skyrmion spin textures. These coffee-bean-shaped objects are observed in real space in thin plates using Lorentz transmission electron microscopy (LTEM). From LTEM imaging alone, it is not clear whether biskyrmions are surface-confined objects, or, analogous to skyrmions in noncentrosymmetric helimagnets, 3D tube-like structures in a bulk sample. Here, the biskyrmion form factor is investigated in single- and polycrystalline-MnNiGa samples using small-angle neutron scattering. It is found that biskyrmions are not long-range ordered, not even in single crystals. Surprisingly all of the disordered biskyrmions have their in-plane symmetry axis aligned along certain directions, governed by the magnetocrystalline anisotropy. This anisotropic nature of biskyrmions may be further exploited to encode information.

Factors Affecting the Development of Confidence Among Surgical Trainees.

OBJECTIVE: The objective of this study was to explore and better characterize the factors affecting confidence during surgical training. DESIGN: This was a qualitative research study in which we conducted semistructured interviews with surgical residents to explore factors affecting their confidence. SETTING: This study was conducted at the University of Alberta Hospital, a tertiary care center located in Edmonton, Alberta, Canada. PARTICIPANTS: Residents from the University of Alberta General Surgery residency program were invited to participate from each postgraduate year (PGY) 2, 3, and 4 for a total of 7 participants (3 PGY-2, 3 PGY-3, and 1 PGY-4; 3 male, and 4 female). We excluded residents who had completed or were currently enrolled in dedicated research years. RESULTS: Resident confidence was found to be influenced by internal and external factors operating before, during, and after a particular surgical task. Internal factors incorporated personal experiences (including operative experience), personal expectations, self-perception, and individual skill development. External factors involved feedback, patient outcomes, relationships with staff, and working within a supportive environment. Interestingly, residents discussed external social factors more than case volume, technical skills, or underlying knowledge. Residents did not feel that their personal lives (e.g. marital status or having children) directly affected their surgical confidence. Regardless of the factor itself, positive experiences helped build and maintain confidence by providing feelings of reassurance, encouragement, comfort, and acceptance. CONCLUSIONS: Surgical confidence is influenced by a range of internal and external factors. Understanding these factors can help educators improve learning experiences for residents and accelerate their progress towards being confident, independent surgeons.

Disordered skyrmion phase stabilized by magnetic frustration in a chiral magnet.

Magnetic skyrmions are vortex-like topological spin textures often observed to form a triangular-lattice skyrmion crystal in structurally chiral magnets with the Dzyaloshinskii-Moriya interaction. Recently, ß-Mn structure-type Co-Zn-Mn alloys were identified as a new class of chiral magnet to host such skyrmion crystal phases, while ß-Mn itself is known as hosting an elemental geometrically frustrated spin liquid. We report the intermediate composition system Co7Zn7Mn6 to be a unique host of two disconnected, thermal-equilibrium topological skyrmion phases; one is a conventional skyrmion crystal phase stabilized by thermal fluctuations and restricted to exist just below the magnetic transition temperature Tc, and the other is a novel three-dimensionally disordered skyrmion phase that is stable well below Tc. The stability of this new disordered skyrmion phase is due to a cooperative interplay between the chiral magnetism with the Dzyaloshinskii-Moriya interaction and the frustrated magnetism inherent to ß-Mn.

Tuning the multiferroic mechanisms of TbMnO3 by epitaxial strain.

A current challenge in the field of magnetoelectric multiferroics is to identify systems that allow a controlled tuning of states displaying distinct magnetoelectric responses. Here we show that the multiferroic ground state of the archetypal multiferroic TbMnO3 is dramatically modified by epitaxial strain. Neutron diffraction reveals that in highly strained films the magnetic order changes from the bulk-like incommensurate bc-cycloidal structure to commensurate magnetic order. Concomitant with the modification of the magnetic ground state, optical second-harmonic generation (SHG) and electric measurements show an enormous increase of the ferroelectric polarization, and a change in its direction from along the c- to the a-axis. Our results suggest that the drastic change of multiferroic properties results from a switch of the spin-current magnetoelectric coupling in bulk TbMnO3 to symmetric magnetostriction in epitaxially-strained TbMnO3. These findings experimentally demonstrate that epitaxial strain can be used to control single-phase spin-driven multiferroic states.

How Do Surgery Students Use Written Language to Say What They See? A Framework to Understand Medical Students' Written Evaluations of Their Teachers.

BACKGROUND: There remains debate regarding the value of the written comments that medical students are traditionally asked to provide to evaluate the teaching they receive. The purpose of this study was to examine written teaching evaluations to understand how medical students conceptualize teachers' behaviors and performance. METHOD: All written comments collected from medical students about teachers in the two surgery clerkships at the University of Alberta in 2009-2010 and 2010-2011 were collated and anonymized. A grounded theory approach was used for analysis, with iterative reading and open coding to identify recurring themes. A framework capturing variations observed in the data was generated until data saturation was achieved. Domains and subdomains were named using an in situ coding approach. RESULTS: The conceptual framework contained three main domains: "Physician as Teacher," "Physician as Person," and "Physician as Physician." Under "Physician as Teacher," students commented on specific acts of teaching and subjective perceptions of an educator's teaching values. Under the "Physician as Physician" domain, students commented on elements of their educator's physicianship, including communication and collaborative skills, medical expertise, professionalism, and role modeling. Under "Physician as Person," students commented on how both positive and negative personality traits impacted their learning. CONCLUSIONS: This framework describes how medical students perceive their teachers and how they use written language to attach meaning to the behaviors they observe. Such a framework can be used to help students provide more constructive feedback to teachers and to assist in faculty development efforts aimed at improving teaching performance.

"I have the right to a private life": medical students' views about professionalism in a digital world.

BACKGROUND: Social media site use is ubiquitous, particularly Facebook. Postings on social media can have an impact on the perceived professionalism of students and practitioners. AIMS: In this study, we explored the attitudes and understanding of undergraduate medical students towards professionalism, with a specific focus on online behaviour. METHODS: A volunteer sample of students (n = 236) responded to an online survey about understanding of professionalism and perceptions of professionalism in online environments. Respondents were encouraged to provide free text examples and to elaborate on their responses through free text comments. Descriptive analyzes and emergent themes analysis were carried out. RESULTS: Respondents were nearly unanimous on most questions of professionalism in the workplace, while 43% felt that students should act professionally at all times (including free time). Sixty-four free text comments revealed three themes: "free time is private time";" professionalism is unrealistic as a way of life"; and "professionalism should be a way of life". CONCLUSIONS: Our findings indicate a disconnect between what students report of what they understand of professionalism, and what students feel is appropriate and inappropriate in both online and real life behaviour. Curriculum needs to target understanding of professionalism in online and real environments and communicate realistic expectations for students.

Learning the CanMEDS roles in a near-peer shadowing program: a mixed methods randomized control trial.

BACKGROUND: The development of competency frameworks, such as CanMEDS, has helped define professional behavior, but programs that translate their theoretical aspects into practical learning are lacking. AIM: To improve instruction of the CanMEDS framework, the University of Alberta implemented a program in which 83 first-year medical students shadowed a first-year resident for eight months. METHODS: A randomized trial compared participants' attitudes and knowledge regarding CanMEDS to controls. A concurrent-triangulation mixed methods design with questionnaires and interviews provided a comprehensive understanding of program experiences. RESULTS: Students reported increasing their understanding of CanMEDS and increased their acceptance of the framework's importance and knowledge of its contents when compared to controls. Residents also reported that their knowledge of CanMEDS had increased. Participants considered the program to be effective for learning CanMEDS and developing professionalism, especially when paired with clinical encounters relevant to given professional roles. CONCLUSION: This simple, low cost, near-peer shadowing program can be useful for teaching professional behavior.

Team-based assessment of medical students in a clinical clerkship is feasible and acceptable.

BACKGROUND: This study describes the development, implementation and evaluation of a team-based, multi-source method of assessment in which students on a clinical clerkship were provided with feedback on their performance as observed by physicians, residents, nurses, peers, patients and administrators. METHODS: The instrument was developed by reviewing existing assessment items and by obtaining input from assessors and students. Numerical data and written comments provided to students were collected, internal consistency was estimated and interviews and focus groups were used to determine acceptability to assessors and students. RESULTS: A total of 1068 assessors completed 3501 forms for 127 students. Internal consistency estimates for each assessment form were acceptable (Cronbach's alpha 0.856-0.948). Each student received an average of 188 words of written feedback divided into an average of 26 'Areas of Excellence' and 5 'Areas for Improvement'. Interviews revealed that the majority of students and assessors interviewed found the method acceptable. CONCLUSIONS: This study demonstrates that a team-based model of assessment based on the principles of multi-source feedback is a feasible and acceptable form of assessment for medical students learning in a clinical clerkship, and has some advantages over traditional preceptor-based assessment. Further studies will focus on the strengths and weaknesses of this novel assessment technique.

"A chance to show yourself" - how do applicants approach medical school admission essays?

BACKGROUND: Although essay questions are used in the admissions process in many medical schools, there has been little research on how applicants respond to essay questions. AIMS: The purpose of this study was to explore how applicants to medical school approach essay questions used in the selection process. METHODS: Qualitative analysis was conducted on 240 randomly selected essays written by individuals applying to a single Canadian medical school in 2007 using a modified grounded theory approach to develop a conceptual framework which was checked in interviews with applicants. RESULTS: Three core variables were identified: "balancing service and reward," "anticipating the physician role," and "readiness." We described the overall approach of applicants as "taking stock," writing about their journeys to the selection process, their experiences of the process itself, and about their anticipated future in medicine. CONCLUSION: Our findings suggest a disconnect between the approach of the applicants (to "show themselves" and be selected as individuals) and the stated intent of the process (to select applicants based on "objective" criteria). Our findings raise important questions about how applicants represent themselves when applying for medical school and suggest that it is important to understand the applicant's point of view when developing questions for selection processes.

Combined antioxidant therapy reduces pain and improves quality of life in chronic pancreatitis.

Patients with chronic pancreatitis (CP) typically suffer intractable abdominal pain that is resistant to most analgesic strategies. Recent research indicates that the pain of CP may be in part due to oxygen free radical induced pancreatic damage. Using a randomized, double-blind, placebo-controlled crossover trial, we evaluated the efficacy of a combined antioxidant preparation in the management of CP. Patients with confirmed chronic pancreatitis (N = 36) were randomized to receive treatment with either Antox, which contains the antioxidants selenium, betacarotene, L-methionine, and vitamins C and E, or placebo for 10 weeks. Each group of patients then switched to receive the alternative treatment for a further 10 weeks. Markers of antioxidant status were measured by blood sampling, whereas quality of life and pain were assessed using the SF-36 questionnaire. Nineteen patients completed the full 20 weeks of treatment. Treatment with Antox was associated with significant improvements in quality of life in terms of pain (+17 antioxidant vs. -7 placebo), physical (+9 vs. -3) and social functioning (+8 vs. -7), and general health perception (+10 vs. -3). We conclude that treatment with antioxidants may improve quality of life and reduce pain in patients suffering from chronic pancreatitis.

Intravascular synovial sarcoma of the external iliac vein and reconstruction with the superficial femoral vein.

Intravascular synovial sarcoma is a rare neoplasm that arises in large veins of the junctional zone between the proximal leg and lower trunk in adult women. Herein we report the first case of an intravascular synovial sarcoma of the external iliac vein. It was successfully treated with neoadjuvant radiotherapy, radical excisional surgery, and combined arterial and venous reconstruction. Intravascular synovial sarcoma should be considered in the differential diagnosis of any adult woman with deep venous thrombosis and a mass of the femoral or iliac venous system.