Nuclear Magnetic Resonance in α- and β-Manganese Metals

Nuclear magnetic resonance studies on Mn 55 in α- and β-Mn metals have been made by both the steady and the pulse methods. Nuclear spin-lattice relaxation time T 1 and spin-spin relaxation time T 2 were measured by the pulse method in the temperature range of 1.5°K to 77°K. The measured value of T 1 T of β-Mn keeps a constant value of 7 m sec °K through the temperature range measured. Using both the T 1 T value and the Knight shift, the origin of the effective magnetic field acting on a nucleus in a Mn metal was concerned. T 2 of 0.1 m sec. was observed to be temperature independent. Several nuclear spin-lattice relaxation mechanisms together with the origin of the effective magnetic field in the Mn metal are discussed. T 1 due to the dipole, quadrupole, and orbital interactions is calculated using free electron approximation in which the electronic wave function includes partly p - or d -character. It is shown that the orbital interaction is more effective than those due to the dipole or quadrupole interaction. Mn 55 nuclear magnetic resonance in an antiferromagnetic α-Mn metal was observed by the pulse method in zero external magnetic field and at temperatures of 1.5°K to 4.2°K.