Optical and magneto-optical study of the transparent ionic ferromagnet Rb₂CrCl₄

The Jahn-Teller active fluoroperovskites $A\mathrm{CrF_3}$ $A=\mathrm{Na^+},\mathrm{K^+}$: thermo- and magneto optical correlations as function of the $A$-site

“…The increase in E SA band intensity with increasing magnetic field for NaCrF 3 at 2 K is not observed for KCrF 3 or other related Cr 2+ fluorides, e.g. Rb 2 CrCl 4 in which the E SF transitions decline in intensity with increasing magnetic field [22,23]. The increase could be related to the orbital structure and spin ordering correlations described in the Kugel-Khomskii Hamiltonian [24].…”

Truncated forms of the second-rank orthorhombic Hamiltonians used in magnetism and electron magnetic resonance (EMR) studies are invalid—Why it went unnoticed for so long?

“…(12) and (13) have been used for Rb 2 CrCl 4 and related systems in, e.g. [64][65][66][67][68][69][70][71]. Below only a few selected examples are explicitly provided.…”

Spin dynamics and absorption-band profiles for the planar two-dimensional easy-plane ionic ferromagnet Rb 2 CrCl 4

“…These very weak lines are associated with electronic origins and they have a magnetic dipole character because the approximate symmetry at each Cr2+ site is centrosymmetric Z)4h. The bands in the two selected spectral regions have been discussed (Janke et al 1982) as pure spin-flips and it is now believed that the appropriate assign ments with tetragonal (octahedral) notations are 5B lg (5Eg)-> 3B lg (3Eg(3H)) and N ___ E/cm 1 F ig u r e 7. Influence of a magnetic field .£?//[ 100] in region I at 1.4 K. The magnon occupation number nk is the average value (otk a.ky or (P£ fiP).…”

“…The result of the competition between the ferromagnetic exchange and the anisotropy terms is a structure with spins on neighbouring ions canted at an angle + 6 from the easy [110] direction (Janke et al 1983) and the occurrence of a small gap in the acoustic spin-wave branch. Applying a magnetic field along one of the relatively hard [100] or hard [001] axes, this gap should first decrease to zero at a critical field B& or Bc and then rise again (Elliott et al 1980; Harrop The unusual temperature dependence of the visible absorption bands in Rb2CrCl4 has been the subject of several experimental studies (Day 1979 ;Janke et al 1982). Attention has concentrated on two regions, near 631 an 530 nm.…”

“…Although the main features of the temperature-and field-dependence of intensity of the hot magnon sidebands are reasonably well understood (Gregson et al 1976;Janke et al 1982), the method of simulating the band profiles (Elliott et al 1980) has not been given in detail. Harrop (1981) calculated band shapes by numerical methods involving a mesh of points throughout the Brillouin zone, in the absence or presence of a relatively large (greater than 1 T) magnetic field.…”