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The magnetic field dependences of the rotation of the plane of polarization of light and the magnetization in single crystals of the ferroborate TbFe3(BO3)4 are studied. The main contribution to the magnetic field-induced rotation of the plane of polarization is found to be from the magnetic subsystem of the terbium ions. [ABSTRACT FROM AUTHOR]

In the region of the 6A1g(6S)→4A1g,4Eg(4G) optical transition, the absorption spectrum of the quasi-two-dimensional antiferromagnet MnPS3 has an exciton-magnon structure. It includes a pure exciton line with a wave number of 21223.5 cm-1 and an exciton-magnon band with a peak at 21328 cm-1 for T=1.7 K. The spectra are studied at temperatures ranging from 1.7 to 80 K and with external magnetic fields up to 60 kOe. In a magnetic field oriented along the easy axis z, splitting of the exciton line is observed owing to the nonequivalence of the magnetic sublattices with respect to an external field. The behavior of the split components in the region of the spin-orientation transition (35-41 kOe) is typical of second order phase transitions. [ABSTRACT FROM AUTHOR]

In the region of the 6A1g(6S)→4A1g,4Eg(4G) optical transition, the absorption spectrum of the quasi-two-dimensional antiferromagnet MnPS3 has an exciton-magnon structure. It includes a pure exciton line with a wave number of 21223.5 cm-1 and an exciton-magnon band with a peak at 21328 cm-1 for T=1.7 K. The spectra are studied at temperatures ranging from 1.7 to 80 K and with external magnetic fields up to 60 kOe. In a magnetic field oriented along the easy axis z, splitting of the exciton line is observed owing to the nonequivalence of the magnetic sublattices with respect to an external field. The behavior of the split components in the region of the spin-orientation transition (35-41 kOe) is typical of second order phase transitions. [ABSTRACT FROM AUTHOR]

The antiferromagnetic resonance (AFMR) spectra along the principal magnetic axes x, y, z of the compound Mn2P2S6 have been investigated in detail in a wide range of frequencies (8–142 GHz) and magnetic fields (up to 75 kOe) at T=4.2 K. It is shown that this compound is a biaxial magnetic substance. At H=0, there are two gaps in the spin-wave spectrum: (101.46±0.1) and (115.52±0.1) GHz. The AFMR data were used to determine the effective magnetic-anisotropy fields: Ha1=0.619 kOe and Ha2=0.803 kOe. An anomalous interaction of the AFMR branches in Mn2P2S6 has been detected, along with the appearance of coupled spin–spin oscillations of the same symmetry. An additional absorption in the AFMR spectrum is a local mode associated with breakdown of translational order in a low-dimension magnet. It is shown for the first time that the appearance of additional absorption peaks depends on the sample-cooling rate. It is proven that the observed peaks are associated with the internal modes of the domain boundaries. [ABSTRACT FROM AUTHOR]

The influence of photoillumination on the magnetic and transport properties of epitaxial thin films of the manganite Pr0.6La0.1Ca0.3MnO3 is investigated. It is found that illuminating films with He–Ne laser light increases their magnetization and decreases their electric resistance, stimulating an antiferromagnetic-insulator—ferromagnetic-metal phase transition, which is observed in this crystal in a magnetic field at low temperatures. It is shown that the phase-transition field is appreciably lower after the films are photoilluminated. It is concluded that photoillumination gives rise to the formation and growth of ferromagnetic metallic clusters inside an antiferromagnetic insulating phase. The mechanism of the effect of light on the magnetic and electric states of the manganite Pr0.6La0.1Ca0.3MnO3 could be related with photoinduced electron transfer from Mn3+ to Mn4+ ions, which results in melting of the charge ordering present in this manganite in the antiferromagnetic insulating state, and gives rise to a transition of the crystal into a ferromagnetic metallic phase. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The effect of linearly polarized light illumination on the metamagnetic phase transition in the antiferromagnetic garnet CaMnGaO is studied. The crystal is exposed to light propagating both along the tetragonal axis [001] and along the [100] direction. In both cases, a change of the field H of the metamagnetic phase transition is observed under illumination, and this change depends on the orientation of plane or polarization of the light with respect to the crystal axes. In the first case, the value of H decreases on exposure to light with the polarization and increases on exposure to light with the polarization. In the second case, the value of H decreases irrespective of the orientation of the plane of polarization of the light with respect to the crystal axes. However, the magnitudes of the change of H are different for light with the polarization and with the polarization. The change of the field of the metamagnetic phase transition in the second case is much larger than in the first case. A phenomenological theory of the photomagnetic effects observed in the antiferromagnetic garnet CaMnGeO is developed. It is shown that the effect of light illumination on the metamagnetic phase transition is related to the photoinduced magnetic moment in this antiferromagnet. The magnetic moment induced by linearly polarized light in the garnet CaMnGeO is detected experimentally by means of a SQUID magnetometer. [ABSTRACT FROM AUTHOR]

The temperature dependences M(T) and field dependences M(H) of the magnetization have been measured in single-crystal TbBaCo4O7 for two magnetic-field directions: H∥c and H⊥c. In the case of H∥c, a magnetic field-induced irreversible transition is detected at low temperatures, accompanied by magnetization jumps on the M(H) dependences. It is shown that the transition field depends on the rate at which the external magnetic field is introduced. [ABSTRACT FROM AUTHOR]

The antiferromagnetic resonance (AFMR) spectra along the principal magnetic axes x, y, z of the compound Mn2P2S6 have been investigated in detail in a wide range of frequencies (8–142 GHz) and magnetic fields (up to 75 kOe) at T=4.2 K. It is shown that this compound is a biaxial magnetic substance. At H=0, there are two gaps in the spin-wave spectrum: (101.46±0.1) and (115.52±0.1) GHz. The AFMR data were used to determine the effective magnetic-anisotropy fields: Ha1=0.619 kOe and Ha2=0.803 kOe. An anomalous interaction of the AFMR branches in Mn2P2S6 has been detected, along with the appearance of coupled spin–spin oscillations of the same symmetry. An additional absorption in the AFMR spectrum is a local mode associated with breakdown of translational order in a low-dimension magnet. It is shown for the first time that the appearance of additional absorption peaks depends on the sample-cooling rate. It is proven that the observed peaks are associated with the internal modes of the domain boundaries. [ABSTRACT FROM AUTHOR]