Itinerant metamagnetism

Low temperature spin reorientation in dysprosium iron garnet

“…The results are in a good agreement with the data obtained on powder sample from 1.3 K to 16 K where the Schottky levels have been calculated [10]. At first, the SR transition is observed with a sharp jump at T SR =14.5±0.5 K in our C p (T) curve which correspond to a spontaneous change from the HT easy direction <111> to the <uuw> angular LT phases as reported and predicted previously [4][5][6][7][8]. At this first order transition temperature T SR a drastic change of the real structure is expected: the rhombohedral distorsion of the R 3 c space group with only two inequivalent magnetic sites [9] is no longer valid below T SR and the symmetry is lowered with the appearance of at least four inequivalent sites of the monoclinic space group C2/c [6].…”

“…At first, the SR transition is observed with a sharp jump at T SR =14.5±0.5 K in our C p (T) curve which correspond to a spontaneous change from the HT easy direction <111> to the <uuw> angular LT phases as reported and predicted previously [4][5][6][7][8]. At this first order transition temperature T SR a drastic change of the real structure is expected: the rhombohedral distorsion of the R 3 c space group with only two inequivalent magnetic sites [9] is no longer valid below T SR and the symmetry is lowered with the appearance of at least four inequivalent sites of the monoclinic space group C2/c [6]. The more recent study of the Mössbauer spectra of DyIG [11] clearly confirm also that the SR phase transition occur at 15 K down 4.2 K but reveal in the 45 K-295 K temperature range, that the Mössbauer spectral components are consistent with a crystal with a reduced symmetry from cubic to rhombohedral but with the space group R 3 .…”

“…The many interesting magnetic properties at low temperature which is often taken in account including strong magnetocrystalline anisotropy, spontaneous non-collinear magnetic structures (double umbrella-type), SR and FI magnetic phase transitions and their complicated experimental MPD in the vicinity of the compensation temperature, have been thoroughly reviewed by Guillot [2] and Zvezdin [3]. The occurrence of the so-called <uuw> and <uv0> angular LT phases where the iron sublattices magnetisation M Fe l i e s on a low symmetry direction are studied experimentally [4,5,6] and theoretically [7,8] by using different phenomenological models based on the generalized spin effective Hamiltonian broadly applicable to such magnetic transitions. So, the revisiting of these SR phase transitions would give a good chance to improve our knowledge in several topics especially detailed more information about the real non collinear magnetic structure of the RE 3+ at low temperature.…”

Temperature Evolution of the Double Umbrella Magnetic Structure in Terbium Iron Garnet

“…According to the earlier precise X-ray diffraction measurements of the rhombohedral distortions carried out on single crystals of the terbium-yttrium iron garnet system (Levitin et al, 1983), the choice of the subgroup R 3 c seems more appropriate. This choice will be confirmed later by our high field magnetization measurements and the use of the method of "the symmetry lowering device" (Bertaut, 1981) which is connected with representation analysis of Bertaut (Bertaut, 1968(Bertaut, , 1971(Bertaut, , 1972.…”

THE EFFECT OF SMALL SUBSTITUTIONS OF Gd ON THE MAGNETIC PROPERTIES OF SYSTEM Y〖(〖Co〗_(1-x) 〖Al〗_x)〗_2

“…One of characteristic manifestations of such instability is zonal metamagnetism induced by the field of the firstorder phase transition from the paramagnetic to ferromagnetic state. This phenomenon is associated with a special form of energy dependence of the density of states in the vicinity of the Fermi level, which facilitates an increase in with applied magnetic field at < and at > , where is the coefficient of exchange interaction [1]. When the coefficient of exchange interaction is positive, the exchange interaction strives to orient the spins of electrons (and hence the magnetic moments) parallel to each other.…”