Alexander Mukhin

Alexander Mukhin
Russian Academy of Sciences | RAS · A.M Prokhorov General Physics Institute

About

280
Publications
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5,861
Citations
Citations since 2016
52 Research Items
2246 Citations
20162017201820192020202120220100200300400
20162017201820192020202120220100200300400
20162017201820192020202120220100200300400
20162017201820192020202120220100200300400

Publications

Publications (280)
Article
Full-text available
We developed an optical cryostat with a sample-rotation unit for polarization-sensitive measurement in terahertz (THz) and infrared (IR) ranges. The cryostat, in combination with two metal-grid polarizers, provides full control of mutual orientation of the sample's crystallographic axes and the light polarization plane. Importantly, this control is...
Article
Experimental and theoretical studies of the magnetoelectric properties of a series of Fe langasite multiferroics (Ba3NbFe3Si2O14, Ba3TaFe3Si2O14, and Sr3TaFe3Si2O14) with planar triangular spiral magnetic structure and double chiral magnetic order have been carried out. Magnetic field induced electric polarization is observed to emerge in the basal...
Article
We measured the heat capacity, magnetic susceptibility, magnetization, magnetoelectric effect, and optical spectra of samarium chromium borate crystals. It was found that, in SmCr3(BO3)4 single crystals, structures with the space groups R32 and C2/c may coexist. Magnetic phase transitions were discovered at temperatures TN1=7.8±0.5K, TN2=6.7±0.5K,...
Article
Full-text available
Inelastic neutron scattering spectra in the antiferromagnetic ferroborates Nd1−xTbxFe3(BO3)4 (x = 0, 0.1, 0.2, and 1) reveal various magnetic excitations of the interacting iron and rare-earth subsystems. We observe an evolution of the magnetic system from “easy-plane”, in the Tb-free (x = 0) case, to “easy-axis” anisotropy for samples substituted...
Article
Full-text available
A dense system of independent oscillators, connected only by their interaction with the same cavity excitation mode, will radiate coherently, which effect is termed superradiance. In several cases, especially if the density of oscillators is high, the superradiant decay of the oscillators’ excited state may dominate the intrinsic relaxation process...
Article
Full-text available
The polarizing spectroscopy techniques in visible range optics have been used since the beginning of the 20th century to study the anisotropy of crystals based on birefringence and optical activity phenomena. On the other hand, the phenomenon of X-ray optical activity has been demonstrated only relatively recently. It is a selective probe for the e...
Article
The magnetic structure is usually determined by the neutron diffraction measurements. However, in the case of complex multisublattice magnetics, this method fails to give an unambiguous result. Here, on the example of multiferroic HoFe3(BO3)4, we show that in the case of rare-earth (RE) compounds the right magnetic structure can be determined by ad...
Preprint
Full-text available
A dense system of independent oscillators, connected only by their interaction with the same cavity excitation mode, will radiate coherently, which effect is termed superradiance. In several cases, especially if the density of oscillators is high, the superradiance may dominate the intrinsic relaxation processes. This limit can be achieved, e.g., w...
Article
Full-text available
Violation of time reversal and spatial inversion symmetries has profound consequences for elementary particles and cosmology. Spontaneous breaking of these symmetries at phase transitions gives rise to unconventional physical phenomena in condensed matter systems, such as ferroelectricity induced by magnetic spirals, electromagnons, non-reciprocal...
Preprint
Full-text available
Violation of time reversal and spatial inversion symmetries has profound consequences for elementary particles and cosmology. Spontaneous breaking of these symmetries at phase transitions gives rise to unconventional physical phenomena in condensed matter systems, such as ferroelectricity induced by magnetic spirals, electromagnons, non-reciprocal...
Article
We present a theoretical study of the spin dynamics in perovskite-like multiferroics with homogeneous magnetic order in the presence of external magnetic and electric fields. A particular example of such material is BeFeO 3 in which the spin cycloid can be suppressed by application of external magnetic field, doping or by epitaxial strain. Understa...
Article
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 Bi2Fe4O9 materializing a Cairo pentagonal lattice. We present the spin wave excitations in the magnetically ordered state, obt...
Article
Full-text available
CuO is the only known binary multiferroic compound, and due to its high transition temperature into the multiferroic state, it has been extensively studied. In comparison to other prototype multiferroics, the nature and even the existence of the high-temperature incommensurate paraelectric phase (AF3) were strongly debated—both experimentally and t...
Article
Magnetoelectric coupling in multiferroic materials opens new routes to control the propagation of light. The new effects arise due to dynamic magnetoelectric susceptibility that cross-couples the electric and magnetic fields of light and modifies the solutions of Maxwell equations in media. In this paper, two major effects will be considered in det...
Article
We developed an optical cryostat with a sample-rotation unit for polarization-sensitive measurement in terahertz (THz) and infrared (IR) ranges. The cryostat, in combination with two metal-grid polarizers, provides full control of the mutual orientation of the sample’s crystallographic axes and the light polarization plane. Importantly, this contro...
Preprint
Magnetoelectric coupling in multiferroic materials opens new routes to control the propagation of light. The new effects arise due to dynamic magnetoelectric susceptibility that cross-couples the electric and magnetic fields of light and modifies the solutions of Maxwell equations in media. In this paper two major effects will be considered in deta...
Preprint
Full-text available
A peculiar non collinear magnetic order is known to be stabilized in Bi2Fe4O9 materializing a Cairo pentagonal lattice. Using inelastic neutrons scattering, we have measured the spin wave excitations in the magnetically ordered state. The magnetic excitations have been modeled to determine the frustrated superexchange interactions at the origin of...
Preprint
Materials with optical activity can rotate the polarization plane of transmitted light. The most typical example is the natural optical activity, which has the symmetry property of changing sign after space inversion but being invariant to time inversion. Faraday rotation exhibits the opposite: it is invariant to space inversion but changes sign af...
Article
Crystals of M-type Co-substituted strontium hexaferrites have been grown for the first time by floating zone melting technique. Homogeneous crystals are obtained from the charge with composition SrCoxMg0.125xFe12−1.125xO19 (x = 0.1, 0.2 and 0.3). The increase of cobalt content above 0.3 (x > 0.3) results in changing of hexaferrite-like structures f...
Article
Full-text available
Materials with optical activity can rotate the polarization plane of transmitted light. The most typical example is the natural optical activity, which has the symmetry property of changing sign after space inversion but being invariant to time inversion. Faraday rotation exhibits the opposite: It is invariant to space inversion but changes sign af...
Article
Magnetic structure of the substituted multiferroics-ferroborates Nd0.9Tb0.1Fe3(BO3)4 and Nd0.8Tb0.2Fe3(BO3)4 were determined in the framework of a self-consistent refinement of the single crystal neutron diffraction data. The small substitution of Nd for Tb leads to the reorientation of the main antiferromagnetic vector L from the basal plane towar...
Article
The evolution of the low temperature antiferromagnetic conical (characterized by two, commensurate and incommensurate propagation vectors), and the high temperature collinear spin arrangements of the 20% Co-doped MnWO4 multiferroic has been studied in the presence of magnetic field up to 60 T by means of macroscopic magnetic and pyroelectric measur...
Article
We report a single-crystal neutron diffraction study of the magnetic structure of the multiferroic compound YbMnO3, a member of the hexagonal manganite family, in zero field and under a magnetic field applied along the c axis. We propose a scenario for the zero-field magnetic ordering and for the field-induced magnetic reorientation of the Mn atom...
Preprint
Full-text available
We report single-crystal neutron diffraction study of the magnetic structure of the multiferroic compound YbMnO$_3$, a member of the hexagonal manganite family, in zero-field and under a magnetic field applied along the $c$-axis. We propose a scenario for the zero-field magnetic ordering and for the field-induced magnetic reorientation of the Mn an...
Article
Full-text available
We present a systematic powder neutron diffraction study on Sr-based M-type hexaferrites SrScxFe12−xO19 using high-resolution and high-flux instruments. We have derived the magnetic configurations for the compounds with x=1.4, 1.6, and 1.8 at room temperature and at 2 K revealing a ferrimagnetic structure and a complex conical magnetic structure, r...
Article
The orthorhombic rare-earth manganate Eu1−xHoxMnO3 (x≥0.15) exhibits multiferroism below TMF∼25K, with a static electric polarization caused by a cycloidal spin order. We observe transient disorder effects in the crystal lattice in a very narrow temperature interval at the onset of the multiferroic ordering. This disorder manifests itself in a dist...
Article
The Tb<sup>3+</sup> (4f<sup>8</sup>) crystal-field (CF) excitations and the infrared phonons in TbMnO<sub>3</sub> 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...
Article
Full-text available
Electric manipulation of magnetic properties is a key problem of materials research. To fulfil 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 multifer...
Article
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In this paper, we present a detailed Raman study of the non-multiferroic compounds PrMnO3 and NdMnO3 and the multiferroic compounds TbMnO3 and DyMnO3 as a function of temperature and magnetic field. All studied systems show anomalous phonon shifts close to the Néel transition TN. In PrMnO3 and NdMnO3, the frequency softenings are partly attributed...
Article
Full-text available
Magnetic excitations and exchange interactions in multiferroic NdFe3(BO3)4 were studied by inelastic neutron scattering in the phase with commensurate antiferromagnetic structure. The observed spectra were analyzed in the frame of the linear spin-wave theory. It was shown that only the model, which includes the exchange interactions within eight co...
Article
Full-text available
Materials showing anisotropic magnetocaloric effects could open the way for new designs of magnetic cooling. In the paper by Jin et al. [Phys. Rev. B 83, 184431 (2011)], a rotating magnetocaloric effect was pointed out in TbMnO3 single crystals. The reported effect arises from the rotation of TbMnO3 crystals between their b and a axes. However, in...
Article
Full-text available
Slightly Co-doped MnWO4 at the lowest 5% Co concentration, for which the multiferroic cycloidal phase becomes a ground state, has been studied in magnetic fields up to 60 T by bulk magnetic and electric polarization measurements along different crystallographic directions. The field induced magnetic transitions up to 12 T and the ways they proceed...
Article
Full-text available
Floating zone melting method with optical heating is elaborated to grow single crystals of the substituted hexaferrites BaTixCoxFe12-2xO19 and SrxTixCoxFe12-2xO19 (0.8 ≤ x ≤ 2). The dynamics of the growth process is studied and results of the analysis of impurity phases appearing in the initial stages of the crystal growth are pre-sented. Compositi...
Article
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Single crystals of spinel Co2TiO4, CoTiO3 of ilmenite structure and pseudobrookite CoTi2O5 were grown by means of zone melting equipment URN-2-ZM. The growth processes were performed in an air atmosphere with a speed ∼10 mm/h and a final annealing of the crystal at temperature of 1250 °C. Co2TiO4 and CoTi2O5 crystals were obtained with a diameter o...
Article
The anisotropic magnetic and magnetoelectric properties of single crystals of substituted M-type SrScxFe12 – xO19 (x = 1.4–1.7) hexaferrites are studied at temperatures of 2–800 K in magnetic fields up to 50 kOe. A spontaneous transition from a collinear ferrimagnetic single-axis phase to a conical structure is detected in all compositions, the tra...
Article
The anisotropic magnetoelectric properties of an ytterbium aluminum borate YbAl (BO single crystal having noncentrosymmetric crystal structure (space group R32) are studied, including the orientational, field, and temperature dependences of the polarization in magnetic fields up to 5 T in the temperature range of 2–300 K. It has been shown experime...
Article
Full-text available
Spectroscopic investigation and specific heat and magnetic susceptibility measurements of SmCr3(BO3)4 crystals were performed. The spectra of the Sm3+ and Cr3+ ions in samarium chromium borate were calculated and parameters of the exchange interactions between the nearest chromium ions, chromium and samarium ions were determined. Three phase transi...
Article
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The orthorhombic rare-earth manganite compounds RMnO3 show a global magnetic order for , and several representatives are multiferroic with a cycloidal spin ground state order for . We deduce from the temperature dependence of spin–phonon coupling in Raman spectroscopy for a series of RMnO3 compounds that their spin order locally persists up to abou...
Article
We present macroscopic and neutron diffraction data on multiferroic lightly Co doped Ni3V2O8. The magnetic H−T phase diagrams have been derived from magnetization and electric polarization measurements with field directions parallel to the principal crystallographic axes. While the phase diagram for H∥b is very similar to that of the parent compoun...
Article
Dynamic magnetic properties of magnetoelectric TmAl3(BO3)4 borate have been investigated by terahertz spectroscopy. Crystal-field transitions within the ground multiplet H36 of Tm3+ ions are observed and they are identified as magnetic-dipole transitions from the ground singlet A1 to the next excited doublet E of Tm3+ ions. Unexpected fine structur...
Article
Here we present a detailed study of the terahertz and far-infrared response of the mixed perovskite manganite system Eu1–xHoxMnO3 for holmium concentrations x=0.1 and 0.3. We compare the magnetic excitations of the four different magnetically ordered phases (A-type antiferromagnetic, sinusoidally modulated collinear, helical phases with spin planes...
Article
(Mn,Co)WO 4 compounds are regarded as reference spin-induced multiferroics. A comparative study is presented here, within the magnetic symmetry framework, of the incommensurate magnetic orders responsible for the ferroelectric phases of (i) MnWO 4 under a magnetic field ( H || b ) and (ii) Mn 0.90 Co 0.10 WO 4 in the absence of an external field. O...
Article
Eu1−xHoxMnO3 with x<0.5 has an orthorhombic perovskite structure, where the partial substitution of europium by holmium increases the orthorhombic distortion and changes the low-temperature magnetic structure from canted antiferromagnetic to the multiferroic ground state with cycloidal spin arrangement for x>0.2. We employ polarized, temperature-de...
Article
Full-text available
Apart from being so far the only known binary multiferroic compound, CuO has a much higher transition temperature into the multiferroic state, 230 K, than any other known material in which the electric polarization is induced by spontaneous magnetic order, typically lower than 100 K. Although the magnetically induced ferroelectricity of CuO is firm...
Article
Full-text available
Here we present a detailed study of the THz and FIR response of the mixed perovskite manganite system Eu$_{1-x}$Ho$_x$MnO$_3$ for holmium concentrations x = 0.1 and 0.3. We compare the magnetic excitations of the four different magnetically ordered phases (A-type antiferromagnetic, sinusoidally modulated collinear, helical phases with spin planes p...
Data
Supplementary Figures 1-9, Supplementary Notes 1-4 and Supplementary References
Article
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One of the most fascinating and counterintuitive recent effects in multiferroics is directional anisotropy, the asymmetry of light propagation with respect to the direction of propagation. In such case the absorption in a material can be different for opposite directions. Besides absorption, different velocities of light for different directions of...
Article
Full-text available
Electroactive spin excitations (electromagnons), an analog of the low-frequency quasiferromagnetic antiferromagnetic resonance (AFMR) mode in Fe subsystem, are observed in multiferroic rare-earth ferroborates [specifically in SmFe3(BO3)(4)] in the frequency range of 40-150 GHz, which are shown to contribute dominantly to the giant static (quasistat...
Article
Full-text available
Doping Mn1-xCoxWO4 with Co produces a rich magnetic phase diagram with a large number of ferroelectric phases. We present resonant x-ray magnetic scattering experiments in the known collinear AF4 phase of multiferroic Mn0.85Co0.15WO4 showing that Mn and Co spins point to different directions despite they randomly occupy the same crystallographic si...
Article
Full-text available
We present the results of detailed dielectric investigations of the relaxation dynamics in DyMnO$_3$ multiferroic manganite. Strong low-frequency relaxation process near the paraelectric-ferroelectric phase transition is observed. The high frequency mode is directly to the relaxational motion of multiferroic domain walls. We provide an experimental...
Article
Many technological applications are based on electric or magnetic order of materials, for instance magnetic memory. Multiferroics are materials which exhibit electric and magnetic order simultaneously. Due to the coupling of electric and magnetic effects, these materials show a strong potential to control electricity and magnetism and, more general...
Article
Single crystals of M-type substitution hexaferrites BaScx Fe12 − x O19 and SrScx Fe12 − x O19 (x = 1.3–1.7) have been grown. Their anisotropic magnetic and magnetoelectric properties have been studied at temperatures of 2–360 K in magnetic fields up to 200 kOe. In all compounds under study, a spontaneous transition from the collinear ferrimagnetic...
Article
We investigate the magnetic-field-induced (H∥b) transition in the reference improper multiferroic MnWO4 using superspace formalism. The distinct superspace group symmetries are determined from single-crystal neutron diffraction. The study of the full magnetic symmetry of the incommensurate magnetic phases under field provides the keys for understan...
Article
Full-text available
The magnetic properties and magnetocaloric performance of the multiferroic hexagonal single crystal DyMnO3 have been explored. A giant anisotropic and reversible magnetocaloric effect (MCE) is observed in the vicinity of the magnetic phase transition from the ferrimagnetic to the antiferromagnetic state at 8 K. This latter was found to be of first-...
Article
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Magnetic properties of multiferroic Eu1-xYxMnO3 with x = 0.2, 0.3 were studied by μSR and Mossbauer spectroscopy. Both compounds are known to become antiferromagnetic with Mn3+ being the only magnetic ion. We find TN = 47±0.5K for x = 0.2 and 45±0.5K for x = 0.3. Below TN three different magnetic states (AFM-1, AFM-2, AFM-3) are formed. The μSR par...
Article
Full-text available
The magnetic and magnetoelectric properties of rare-earth (R = Tm, Ho, and Tb) aluminum borates were studied. Magnetic susceptibility of the crystals was examined. The dependencies of the magnetic susceptibility on the magnitude and direction of magnetic field were calculated. The quantum theory of magnetoelectric effect in Tm, Ho, and Tb aluminum...
Article
MnWO${}_{4}$ is a multiferroic material with spontaneous electric polarization induced by spiral magnetic order. One of its puzzling properties is the so called ``X phase'' that appears at applied magnetic fields above 10 Tesla and in a narrow temperature range at about 10 Kelvin. The phase transition from the low-field incommensurate magnetic cycl...