Spin-orientation phase transitions inNd2CuO4: A compound with noncollinear magnetic structure

Abstract

We report magnetization measurements of ${\mathrm{ND}}_2$ ${\mathrm{CuO}}_4$ single crystals in the temperature range 0.5–4.2 K in static and pulsed magentic fields. Two spin-orientation phase transitions, one of the first order (${\mathit{H}}_{\mathit{c}1}$=4.4 T, H?[100]) and another one of the second order (${\mathit{H}}_{\mathit{c}2}$=0.75 T, H?[110]), were observed at 0.7 K for different field orientation. This allows us to conclude that at low temperatures the magnetic moments of the Nd ions (and most probably of the Cu ions) order in the antiferromagnetic noncollinear crosslike structure. In the pulsed-magnetic-field experiments we have found a strong magnetocaloric effect in ${\mathrm{Nd}}_2$ ${\mathrm{CuO}}_4$.