Magnetoelastic Interactions in Ionicπ-Electron Systems: Magnetogyration

Abstract

the field between 0.43 and 2.9 T as we expect for the naf phase. The maximum shift, 1.6 G, in the shoulder of the observed line must equal the maximum possible demagnetizing field M/M 0 x (3.3 G). This gives M/M 0^ 0.5 and is in relatively good agreement with the results of Ref. 2 and our model.We wish to thank D. D. Osheroff, T. C. Prewitt, T. M. Goodkind, and E. D. Adams for communicating their preliminary results, and J. A. Cowen and A. Landesman for many discussions.The alkali hyper oxides A + 0 2 " (A =Na,K,Rb,Cs) are model substances to investigate TT-electron magnetism. 1 * 2 The small symmetric and inorganic molecule anion, effectively a "pseudohalide," gives rise to interesting magnetic order. The peculiarities of the hyperoxide ion 0 2 " are important for the understanding of the many fascinating properties of the A0 2 : (i) The magnetic moment is localized on a (2p)ir g orbital, (ii) The ground state X 2 U g of the free molecule ion is or-

Recent results in solid state chemistry of ionic ozonides, hyperoxides, and peroxides

“…More recently it has been confirmed by EPR and AFMR techniques [110,126], as well as specific-heat measurements [109,130]. Careful in vestigation of the magnetic behavior of potassium hyperoxide revealed a very uncommon phe nomenon called magnetogyration [110]. groups [110].…”

“…For example, Zeeman-splitting of the ground state of 02~(^ng) depends on both the orientation of the anion 1 s molecular axis as well as the crystal field splitting.Thus, magnetiza tion gives rise to a change in orientation of the anion's molecular axis [ 109]. In fact, such magnetoelastic interactions (magnetogyration) have been observed in the case of potassium hyperoxide [110,111,112].…”

“…Initially K0 2 was characterized as exhibiting metamagnetism at low temperatures [109,126].However, more recently AFMR, EPR and two magnon spectroscopy (FIR) experiments using single crystals of KO2 have been reported, which sup port a spin-flop (SF) behavior rather than metamagnetism [110,129]. Finally, the complete magnetic phase-diagram ofK(>2 at low temperatures has been reported (see Fig.…”

“…Finally, the complete magnetic phase-diagram ofK(>2 at low temperatures has been reported (see Fig. 13) [110]. Sin gle crystal EPR and AFMR studies produced a detailed knowledge of the geometrical orientati on of the molecular axes of the O2" anions in IV-KO2 [129]· Moreover, in V-KO2, the molecu lar orientation has been determined from EPR data, which also yielded information on the do main structure [ 129].…”

“…were performed [109,110,113,[127][128][129]. Initially K0 2 was characterized as exhibiting metamagnetism at low temperatures [109,126].However, more recently AFMR, EPR and two magnon spectroscopy (FIR) experiments using single crystals of KO2 have been reported, which sup port a spin-flop (SF) behavior rather than metamagnetism [110,129].…”