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Oblique triangular antiferromagnetic phase in CsCu$_{1-x}$Co$_x$Cl$_3$

T. Ono·T. Kato·H. Tanaka·A. Hoser·N. Stusser·U. Schotte
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Abstract

The spin-1/2 stacked triangular antiferromagnet CsCu$_{1-x}$Co$_x$Cl$_3$ with $0.015<x<0.032$ undergoes two phase transitions at zero field. The low-temperature phase is produced by the small amount of Co$^{2+}$ doping. In order to investigate the magnetic structures of the two ordered phases, the neutron elastic scattering experiments have been carried out for the sample with $x\approx 0.03$. It is found that the intermediate phase is identical to the ordered phase of CsCuCl$_3$, and that the low-temperature phase is an oblique triangular antiferromagnetic phase in which the spins form a triangular structure in a plane tilted from the basal plane. The tilting angle which is 42$^{\circ}$ at $T=1.6$ K decreases with increasing temperature, and becomes zero at $T_{\rm N2} =7.2$ K. An off-diagonal exchange term is proposed as the origin of the oblique phase.

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T. Ono, T. Kato, H. Tanaka, A. Hoser, N. Stusser, U. Schotte. 2000-10-25. Oblique triangular antiferromagnetic phase in CsCu$_{1-x}$Co$_x$Cl$_3$. https://doi.org/10.1103/physrevb.63.224425

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