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Sci Rep ; 11(1): 23626, 2021 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-34880294


We show a method to control magnetic interfacial effects in multilayers with Dzyaloshinskii-Moriya interaction (DMI) using helium (He[Formula: see text]) ion irradiation. We report results from SQUID magnetometry, ferromagnetic resonance as well as Brillouin light scattering results on multilayers with DMI as a function of irradiation fluence to study the effect of irradiation on the magnetic properties of the multilayers. Our results show clear evidence of the He[Formula: see text] irradiation effects on the magnetic properties which is consistent with interface modification due to the effects of the He[Formula: see text] irradiation. This external degree of freedom offers promising perspectives to further improve the control of magnetic skyrmions in multilayers, that could push them towards integration in future technologies.

Hippokratia ; 19(2): 125-30, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-27418760


OBJECTIVE: The objective of this study was to determine the efficacy of the exercises administered to stroke patients with the balance trainer (BALANCE-trainer, 07001-001(TM)) on balance, level of independence and ambulation parameters. MATERIAL AND METHOD: Fifty patients with hemiplegia were randomized into either study group or control group. Patients in the control group received 30 sessions of conventional rehabilitation program and patients in the study group were trained with balance trainer in addition to conventional rehabilitation program. Balance level and postural control were evaluated with Berg Balance Scale (BBS) and Timed-Up and Go Test (TUG). Their functional statuses were evaluated using Functional Independence Measure (FIM). Evaluations were repeated following the six-week rehabilitation program. RESULTS: Of the 50 participants, 19 were women (38%) and 31 were men (62%). The mean age was 57.1 ± 9.2 years. The time that elapsed after stroke was 87.3 ± 26.3 days. Statistically significant improvements were noted in BBS, TUG and FIM in intra-group evaluations for both groups. Statistically significant improvements were documented in BBS and TUG levels for inter-group evaluation (respectively p =0.038, p =0.025), while the difference in FIM levels was not statistically significant (p >0.05). CONCLUSION: Positive impact of balance trainer on balance and postural control was demonstrated in stroke patients in the current study. Hippokratia 2015; 19 (2):125-130.

Phys Rev Lett ; 112(2): 026601, 2014 Jan 17.
Artículo en Inglés | MEDLINE | ID: mdl-24484033


We show experimental evidence of magnetization switching in a single (Ga,Mn)(As,P) semiconducting ferromagnetic layer, attributed to a strong reduction of the magnetization and the anisotropy due to current injection. The nucleation of magnetization reversal is found to occur even in the absence of a magnetic field and to be both anisotropic and stochastic. Our findings highlight a new mechanism of magnetization manipulation based on spin accumulation in a semiconductor material.

J Phys Condens Matter ; 25(34): 346001, 2013 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-23883527


The magnetic anisotropy of the ferromagnetic semiconductor (Ga, Mn) (As, P) is studied in a material-specific microscopic k ⋅p approach. We calculate the electronic energy band structure of (Ga, Mn) (As, P) quaternary ferromagnetic alloys using a 40-band k ⋅p model and taking into account the s, p-d exchange interaction and the strain of the (Ga, Mn) (As, P) layer on a GaAs substrate. We determine the variations of the carrier effective masses in the strained (Ga, Mn) (As, P)/GaAs system. The magnetic anisotropy constants obtained from our simulations using a mean-field model are compared with the experimental ones determined by ferromagnetic resonance spectroscopy on a set of samples with constant manganese concentration and varying phosphorus concentration. An excellent quantitative agreement between experiment and theory is found for the uniaxial out-of-plane and cubic in-plane anisotropy parameters.

Phys Rev Lett ; 109(10): 106603, 2012 Sep 07.
Artículo en Inglés | MEDLINE | ID: mdl-23005314


Electrical spin injection into semiconductors paves the way for exploring new phenomena in the area of spin physics and new generations of spintronic devices. However the exact role of interface states in the spin injection mechanism from a magnetic tunnel junction into a semiconductor is still under debate. In this Letter, we demonstrate a clear transition from spin accumulation into interface states to spin injection in the conduction band of n-Ge. We observe spin signal amplification at low temperature due to spin accumulation into interface states followed by a clear transition towards spin injection in the conduction band from 200 K up to room temperature. In this regime, the spin signal is reduced to a value compatible with the spin diffusion model. More interestingly, the observation in this regime of inverse spin Hall effect in germanium generated by spin pumping and the modulation of the spin signal by a gate voltage clearly demonstrate spin accumulation in the germanium conduction band.