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1.
Zh Nevrol Psikhiatr Im S S Korsakova ; 122(6. Vyp. 2): 84-90, 2022.
Article in Russian | MEDLINE | ID: mdl-35797201

ABSTRACT

The opinion article is devoted to the analysis of a large-scale comprehensive systematic review of relevant and practically oriented studies of vortioxetine use in depression for the period to 2020. The mechanisms of multimodal action, issues of efficacy and safety of the drug, including direct procognitive effects, effects on anhedonia, anxiety, sleep disorders, analgesic and anti-inflammatory effects are highlighted. An increase in the efficacy of vortioxetine when the dose is increased to 20 mg/day is emphasized. Prospective directions for antidepressant research are outlined.


Subject(s)
Depressive Disorder, Major , Vortioxetine , Depressive Disorder, Major/drug therapy , Humans , Prospective Studies , Systematic Reviews as Topic , Vortioxetine/pharmacology , Vortioxetine/therapeutic use
2.
Phys Rev Lett ; 124(12): 127202, 2020 Mar 27.
Article in English | MEDLINE | ID: mdl-32281858

ABSTRACT

The research field of magnetic frustration is dominated by triangle-based lattices but exotic phenomena can also be observed in pentagonal networks. A peculiar noncollinear magnetic order is indeed known to be stabilized in Bi_{2}Fe_{4}O_{9} materializing a Cairo pentagonal lattice. We present the spin wave excitations in the magnetically ordered state, obtained by inelastic neutron scattering. They reveal an unconventional excited state related to local precession of pairs of spins. The magnetic excitations are then modeled to determine the superexchange interactions for which the frustration is indeed at the origin of the spin arrangement. This analysis unveils a hierarchy in the interactions, leading to a paramagnetic state (close to the Néel temperature) constituted of strongly coupled dimers separated by much less correlated spins. This produces two types of response to an applied magnetic field associated with the two nonequivalent Fe sites, as observed in the magnetization distributions obtained using polarized neutrons.

3.
J Phys Condens Matter ; 30(17): 175602, 2018 May 02.
Article in English | MEDLINE | ID: mdl-29437151

ABSTRACT

The Tb3+ (4f 8) crystal-field (CF) excitations and the infrared phonons in TbMnO3 are studied as a function of temperature and under an applied magnetic field. The phonon energy shifts reflect local displacement of the oxygen ions that contribute to the CF energy level shifts below 120 K and under magnetic field. The CF polarized transmission spectra provide interesting information about the debated nature of the excitations at 41, 65, 130 cm-1. We also evaluate the contribution of the charge transfer mechanism to the magnetoelectric process in TbMnO3 under magnetic field.

4.
Phys Rev Lett ; 120(2): 027203, 2018 Jan 12.
Article in English | MEDLINE | ID: mdl-29376713

ABSTRACT

Electric manipulation of magnetic properties is a key problem of materials research. To fulfill the requirements of modern electronics, these processes must be shifted to high frequencies. In multiferroic materials, this may be achieved by electric and magnetic control of their fundamental excitations. Here we identify magnetic vibrations in multiferroic iron borates that are simultaneously sensitive to external electric and magnetic fields. Nearly 100% modulation of the terahertz radiation in an external field is demonstrated for SmFe_{3}(BO_{3})_{4}. High sensitivity can be explained by a modification of the spin orientation that controls the excitation conditions in multiferroic borates. These experiments demonstrate the possibility to alter terahertz magnetic properties of materials independently by external electric and magnetic fields.

5.
Phys Rev Lett ; 111(22): 227201, 2013 Nov 27.
Article in English | MEDLINE | ID: mdl-24329467

ABSTRACT

All-electrical control of a dynamic magnetoelectric effect is demonstrated in a classical multiferroic manganite DyMnO3, a material containing coupled antiferromagnetic and ferroelectric orders. Because of intrinsic magnetoelectric coupling with electromagnons a linearly polarized terahertz light rotates upon passing through the sample. The amplitude and the direction of the polarization rotation are defined by the orientation of ferroelectric domains and can be switched by static voltage. These experiments allow the terahertz polarization to be tuned using the dynamic magnetoelectric effect.

6.
J Phys Condens Matter ; 25(47): 475403, 2013 Nov 27.
Article in English | MEDLINE | ID: mdl-24172650

ABSTRACT

In hexagonal DyMnO3, Dy(3+) crystal-field excitations are studied as a function of temperature and applied magnetic field. They are complemented with the measurements of infrared active phonon frequency shifts under applied magnetic field at T = 4.2 K. Between TN = 68 K and T = 10 K, the absence of Dy(3+) Kramers doublet splittings at either the C3 or the C3v site symmetries indicates that the Mn(3+) magnetic order effective exchange field has no component parallel to the c-axis at either site. Below T = 10 K, the ground state Kramers doublet splits under the Dy(3+) internal effective field as well as the applied magnetic field. Also, relatively strong infrared active phonon energy shifts are observed in magneto-infrared reflectance measurements at T = 4.2 K, allowing the calculation of the induced electric polarization changes as a function of the applied magnetic field. Such changes are associated with a large magnetoelectric effect in DyMnO3, arising from a charge transfer between Dy(3+) and apical oxygen ions.

7.
J Phys Condens Matter ; 25(6): 066003, 2013 Feb 13.
Article in English | MEDLINE | ID: mdl-23306085

ABSTRACT

Dc-susceptibility measurements and Raman active phonon frequencies of hexagonal DyMnO(3) retrace the Mn(3+) ions antiferromagnetic transition at T(N) ~ 70 K and their spin reorientation at T(SR) ~ 48 K. The temperature evolution of Raman active mode frequencies and their over-hardening are associated with Dy(3+) and Mn(3+) ion displacements below T(N) and with a spin-phonon coupling that involves apical oxygen.


Subject(s)
Magnetics , Manganese Compounds/chemistry , Oxides/chemistry , Oxygen/chemistry , Phonons , Spectrum Analysis, Raman , Models, Molecular , Spin Labels , Temperature
8.
J Phys Condens Matter ; 23(11): 113201, 2011 Mar 23.
Article in English | MEDLINE | ID: mdl-21358023

ABSTRACT

We review the recent experimental findings concerning the magnetic and magnetoelectric excitations in multiferroic manganites with special focus on orthorhombic RMnO(3) (R = rare earth). The dynamics of these materials has attracted special attention recently due to the existence of novel magnetoelectric excitations which were termed electromagnons. In addition to the strong electric activity of the electromagnons, a series of other excitations of magnetic and magnetoelectric nature is observed in the same frequency range as the electromagnons. We summarize the systematics of the existing modes and the current understanding of the underlying mechanisms.

9.
Phys Rev Lett ; 104(9): 097202, 2010 Mar 05.
Article in English | MEDLINE | ID: mdl-20367008

ABSTRACT

Terahertz electromagnetic excitations in the multiferroic TbMnO3 single crystals are investigated across the magnetic field induced rotation of the magnetic spin cycloid. In addition to the electromagnon along the a axis, the detailed polarization analysis of the experimental spectra suggests the existence of an electroactive excitation for ac electric fields of the electromagnetic wave along the crystallographic c axis. This excitation is possibly the electroactive eigenmode of the spin-cycloid in TbMnO3, which has been predicted within the inverse Dzyaloshinskii-Moriya mechanism of magnetoelectric coupling.

10.
J Phys Condens Matter ; 22(35): 356002, 2010 Sep 08.
Article in English | MEDLINE | ID: mdl-21403302

ABSTRACT

The A(1), E(1) and E(2) Raman active modes in hexagonal YMnO(3) and LuMnO(3) single crystals are studied as a function of temperature and compared with previous measurements. In addition to anharmonicity, some phonon frequencies show below T(N) anomalous temperature dependences that reflect the atomic displacements while some other phonon frequencies are more sensitive to the spin-phonon coupling.

11.
Phys Rev Lett ; 102(20): 207208, 2009 May 22.
Article in English | MEDLINE | ID: mdl-19519073

ABSTRACT

We present a detailed dielectric study of the relaxation effects that occur in several perovskite rare-earth manganites, including the multiferroics TbMnO(3) and DyMnO(3). We demonstrate that the strong magnetocapacitive effects, observed for electrical fields E parallel c, are nearly completely governed by magnetic-state induced changes of the relaxation parameters. The multiferroic materials, which undergo a transition into a spiral magnetic state, show qualitatively different relaxation behavior than those compounds transferring into an A-type antiferromagnetic state. We ascribe the relaxations in both cases to the off-center motion of the manganese ions, which in the multiferroic systems also leads to the ferroelectric ordering.

12.
Phys Rev Lett ; 102(10): 107203, 2009 Mar 13.
Article in English | MEDLINE | ID: mdl-19392155

ABSTRACT

Magnetic and magnetoelectric excitations in the multiferroic TbMnO3 have been investigated at terahertz frequencies. Using different experimental geometries we can clearly separate the electroactive excitations (electromagnons) from the magnetoactive modes, i.e., antiferromagnetic resonances. Two antiferromagnetic resonances were found to coincide with electromagnons. This indicates that both excitations belong to the same mode and the electromagnons can be excited by a magnetic ac field as well. In spite of the 90 degrees rotation of the magnetic cycloid in external magnetic fields, the electromagnons are observable for electric ac fields parallel to the a axis only.

13.
J Phys Condens Matter ; 21(38): 386004, 2009 Sep 23.
Article in English | MEDLINE | ID: mdl-21832382

ABSTRACT

We present a micro-Raman study of a high quality Pr(0.5)Ca(0.5)MnO(3) single crystal and thin films on SrTiO(3) and LaAlO(3) substrates. Ten A(g) and seven B(2g) Raman-active modes (simplified symmetry: Pmma space group) have been observed and correlated to charge ordering around T(co) = 240 K and antiferromagnetic spin-orbital ordering at T(N)∼ 170 K. Our data reveal that coherent Jahn-Teller MnO(6) distortions prevail at T

14.
J Magn Reson ; 195(1): 60-6, 2008 Nov.
Article in English | MEDLINE | ID: mdl-18819827

ABSTRACT

Transmission spectra, T(H), of linearly polarized electromagnetic waves through YFeO(3), weak ferromagnet, measured at frequencies nu=96-1000 GHz in long-pulsed magnetic fields (H||k||c-axis, Faraday geometry) exhibit strong rotation of the polarization plane near the quasiferromagnetic AFMR as well as low frequency impurity modes. New ascending impurity branch including five lines was observed at high magnetic field (10-30 T) at 96 GHz and 140 GHz in addition to the known low-field descending impurity branch. Behavior of all the impurity modes assigned to transitions in (6)S(5/2) multiplet of Fe(3+) "impurity" ions in c-sites was described self-consistently by one spin-Hamiltonian. A theoretical calculation of dynamical magnetic susceptibility at AFMR and impurity modes and further simulation of transmission spectra made it possible to describe the main features of the observed spectra T(H). It was found that the T(H) behavior is determined at resonances not only by non-diagonal components of the magnetic susceptibility but also by the anisotropy of the dielectric permittivity (epsilon(xx)(') not equal epsilon(yy)(')), i.e. birefringence.


Subject(s)
Ferric Compounds/chemistry , Yttrium/chemistry , Electromagnetic Fields , Magnetics , Microwaves , Scattering, Radiation , Signal Processing, Computer-Assisted
15.
J Magn Reson ; 170(1): 8-14, 2004 Sep.
Article in English | MEDLINE | ID: mdl-15324753

ABSTRACT

A two-sublattice model has been applied to a canted antiferromagnet including both Dzyaloshinsky-Moria interaction and double-exchange. Static magnetization and frequencies of the antiferromagnetic resonances (AFMR) were calculated for static magnetic fields along the principal crystallographic axes of an orthorhombic crystal. The experimental data for La(0.95)Sr(0.05)MnO3, which include magnetization, positions and excitation conditions of the AFMR modes can be well accounted for using the model calculations.

18.
Vrach Delo ; (3): 55-6, 1989 Mar.
Article in Russian | MEDLINE | ID: mdl-2750121

ABSTRACT

The authors investigated the efficacy of using electromagnetic radiation of extremely high frequency and low intensity (bioresonance therapy) in the treatment of patients with some forms of chronic unspecific pulmonary diseases. The object of the investigation were patients with bronchial asthma, chronic nonobstructive and obstructive bronchitis. The treatment efficacy was 80%.


Subject(s)
Lung Diseases/radiotherapy , Microwaves/therapeutic use , Adult , Chronic Disease , Female , Humans , Male , Middle Aged
19.
Article in Russian | MEDLINE | ID: mdl-3825399

ABSTRACT

The authors studied the characteristics of the hereditary aggravation in probands with schizophrenia first manifested with acute delirious or acute verbal hallucinosis. They also considered the incidence of manifest and latent forms of schizophrenia and the rate of personality anomalies in families of probands with the differentiation of schizoid anomalies by the predominance of sthenic and asthenic features. The frequency of coincidence of the patterns of schizophrenic process among relatives was determined and the data obtained were compared with those in probands from each group. The comparative analysis has shown that the familial background of the studied group of probands reflects the following regularities characteristic of schizophrenia; an increase in the frequency of psychoses of the schizophrenic spectrum as against that in the general population, accumulation of homonomous types of the schizophrenia course and the presence in relatives of abnormalities of the schizophrenic nature. This justifies the referral of the studied forms of psychoses to schizophrenic diseases.


Subject(s)
Delusions/genetics , Hallucinations/genetics , Schizophrenia/genetics , Acute Disease , Adolescent , Adult , Automatism/genetics , Humans , Middle Aged , Schizophrenia, Paranoid/genetics , Schizotypal Personality Disorder/genetics , Syndrome
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