Magnetic phase diagram of Sr${}_{1-x}$Ca${}_x$Co${}_2$P${}_2$

Abstract

In order to study the phase diagram from a microscopic viewpoint, we have measured wTF- and ZF-$\hat{I}{¼}^{+}$SR spectra for the Sr${}_{1-x}$Ca${}_x$Co${}_2$P${}_2$ powder samples with $x=0$, 0.2, 0.4, 0.5, 0.6, 0.8, and 1. Due to a characteristic time window and spatial resolution of $\hat{I}{¼}^{+}$SR, the obtained phase diagram was found to be rather different from that determined by magnetization measurements. That is, as $x$ increases from 0, a Pauli-paramagnetic phase is observed even at the lowest $T$ measured (1.8~K) until $x=0.4$, then, a spin-glass like phase appears at $0.5\le x\le 0.6$, and then, a phase with wide field distribution probably due to incommensurate AF order is detected for $x=0.8$, and finally, a commensurate $A$-type AF ordered phase (for $x=1$) is stabilized below $T_{\mathrm{N}}\sim 80$K. Such change is most likely reasonable and connected to the shrink of the $c$-axis length with $x$, which naturally enhances the magnetic interaction between the two adjacent Co planes.

5 pages, 5 figures, conference paper of muSR2014 (accepted for publication)