Aleksandr A. Mukhin

New mechanism of the spin-reorientation phase transition in neodymium orthochromite

Abstract Using magnetization and magnetostriction measurements we have investigated various field-induced and spontaneous spin-reorientation phase transitions (SRPT) in pure NdCrO 3 and Nd 1- x Eu x CrO 3 ( x = 0, 0.3, 0.5, 0.9) single crystals. Analysis of these data gives evidence that spontaneous Morin type Γ 2 ( G z F x ) − Γ 1 ( G y ) SRPT in Nd 1- x Eu x CrO 3 is determined by a competition between two contributions (Zeeman-like and Van Vleck) in the bc -plane anisotropy energy resulting from an anisotropic Nd-Cr exchange.

Submillimeter and far IR spectroscopy of magneto- and electrodipolar rare-earth modes in the orthoferrite TmFeO3

Abstract Rare-earth modes, originating from magneto- and electrodipolar electronic transitions inside the ground multiplet of the Tm 3+ ion, have been observed in the submillimeter transmission and far IR reflection spectra of the orthoferrite TmFeO 3 . The symmetry of the observed electronic excitations is determined and a classification is presented.

Orthorhombic distortion of Rb2MnCl4 in its antiferromagnetic phase

Rb2MnCl4 was always considered to be an ordinary quasi-two-dimensional uniaxial weakly anisotropic antiferromagnet with the crystallographic c axis as the easy axis. This picture became dubious when a splitting was observed of one of the magnetic modes for an external magnetic field applied perpendicular to the c axis. New magnetic resonance measurements revealed also a splitting of the zero-field antiferromagnetic resonance. All the unexpected phenomena observed in this investigation can be explained in terms of an orthorhombic distortion of Rb2MnCl4 in its antiferromagnetic state, taking into account that all samples are of the multi-domain type below the Neel temperature.