Structural and magnetic properties of a new cubic spinel LiRhMnO${}_4$

Abstract

We report the structural and magnetic properties of a new system LiRhMnO${}_4$ (LRMO) through x-ray diffraction, bulk magnetization, heat capacity and ${}^7$Li nuclear magnetic resonance (NMR) measurements. LRMO crystallizes in the cubic space group $Fd$$\bar{3}$$m$. From the DC susceptibility data, we obtained the Curie-Weiss temperature ${\theta }_{\mathrm{CW}}$ = -26 K and Curie constant $C$ = 1.79 Kcm${}^3$/mol suggesting antiferromagnetic correlations among the magnetic Mn${}^{4+}$ ions with an effective spin $S$ = $\frac{3}{2}$. At $H$ = 50 Oe, the field cooled and zero-field cooled magnetizations bifurcate at a freezing temperature, $T_f$ = 4.45 K, which yields the frustration parameter $f=\frac{\mid {\theta }_{CW}\mid }{T_f}>$5. AC susceptibility, shows a cusp-like peak at around $T_f$, with the peak position shifting as a function of the driving frequency, confirming a spin-glass-like transition in LRMO. LRMO also shows typical spin-glass characteristics such as memory effect, aging effect and relaxation. In the heat capacity, there is no sharp anomaly down to 2 K indicative of long-range ordering. The field sweep ${}^7$Li NMR spectra show broadening with decreasing temperature without any spectral line shift. The ${}^7$Li NMR spin-lattice and spin-spin relaxation rates also show anomalies due to spin freezing near $T_f$.

9 pages, 16 figures, 2 tables

References in corpus (1)

• Band Jahn-Teller Instability and Formation of Valence Bond Solid in a Mixed-Valent Spinel Oxide LiRh2O4