THz ESR Study of Peculiar Co Pyrochlore System GeCo2O4 Using Pulsed High Magnetic Field

Abstract

THz electron spin resonance (ESR) measurements of the spinel compound GeCo2O4, which consists of the Co 2+ pyrochlore structure, were performed. The temperature dependence measurements revealed new antiferromagnetic phases, AF1 and AF2, below TN. Moreover, a wide magnetic field range of ESR study using a single crystal at 1.8 K also revealed various field-induced phases due to the competition between the spin-lattice coupling and the spin-frustration. Critical field resonances were observed at 5.