NMR Study of Pressure-Induced Phase Transition in MnAs

Abstract

The Mn⁵⁵ NMR in MnAs has been observed as a function of pressure up to 7 kbar at 77 K. The NMR is observed at 235 MHz in the hexagonal phase below about 4 kbar, while it is observed between 140 and 175 MHz in the orthorhombic phase above about 4 kbar. In the orthorhombic phase the NMR result is interpreted on the basis of a double spiral spin structure, and the magnetic moment estimated from the hyperfine field suggests a low-spin configulation of Mn atom.