Quasi-quartet crystal electric field ground state in a tetragonal CeAg${}_2$Ge${}_2$ single crystal

Abstract

We have successfully grown the single crystals of CeAg${}_2$Ge${}_2$, for the first time, by flux method and studied the anisotropic physical properties by measuring the electrical resistivity, magnetic susceptibility and specific heat. We found that CeAg${}_2$Ge${}_2$ undergoes an antiferromagnetic transition at $T_{\mathrm{N}}$ = 4.6 K. The electrical resistivity and susceptibility data reveal strong anisotropic magnetic properties. The magnetization measured at $T$ = 2 K exhibited two metamagnetic transitions at $H_{m1}$ = 31 kOe and $H_{m2}$ = 44.7 kOe, for $H\parallel$ [100] with a saturation magnetization of 1.6 ${\mu }_{\mathrm{B}}$/Ce. The crystalline electric field (CEF) analysis of the inverse susceptibility data reveals that the ground state and the first excited states of CeAg${}_2$Ge${}_2$ are closely spaced indicating a quasi-quartet ground state. The specific heat data lend further support to the presence of closely spaced energy levels.

2 pages, 2 figures, Submitted to the proceedings of SCES-07, Houston