Magnetic order in2p-electron systems: Electron paramagnetic resonance and antiferromagnetic resonance in the alkali hyperoxides KO2, Rb

M. Labhart

¹

,

D. Raoux

²

,

W. Känzig

³

et al.

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

“…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.…”

“…Cs02-As summarized in Tables V-VII Measurements of the magnetic susceptibility [109], along with electron-paramagnetic-reso nance (EPR) and antiferromagnetic-resonance (AFMR) data, proved that both rubidium and ce sium hyperoxide order antiferromagnetically with N6el-temperatures of 15 and 9.6 Κ respective ly [129]. The observed anomalies in the adiabadc differential susceptibility, at fields of about 25, 26, and 28 kG in KO2, RbC>2, andCs02, respectively [109], which disappear above the N6el tem peratures, have been assigned to a spin-flop transition [129], TTie magnetic axes have been determined for KO2, RbC>2. and CsC>2 from the relation of the g-tensor (which has been determined by EPR spectroscopy) to the orientation of the O2" groups, combined with the field dependence of the AFMR.…”

“…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].…”

“…Because of this complicated crystallographic domain formation, the exact structure could not be determined by diffraction methods [107]. However, the combination of EPR and AFMR data also yields information about the magnetic structure of KO2 [129]. Anti ferromagnetic order in VI-KO2 below 7.1 Κ at sufficiently low magnetic fields originally was…”

“…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]. Because of this complicated crystallographic domain formation, the exact structure could not be determined by diffraction methods [107].…”