Pressure Effect on the Spin Fluctuations in YMn_2-Mn NQR Study-
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We report the NQR study on the pressure-induced paramagnetic state in the antiferromagnetic (AF) intermetallic compound YMn<SUB>2</SUB> with the Néel temperature T<SUB>N</SUB> =100 K at ambient pressure. From the T variation of the nuclear spin-lattice relaxation rate, <SUP>55</SUP> (1/T<SUB>1</SUB>) of <SUP>55</SUP>Mn above the critical pressure of 4 kbar, the spin fluctuation feature is found to change below a temperature T<SUB>sf</SUB>. At higher temperature than T<SUB>sf</SUB>, the nuclear relaxation behavior is well described in terms of the self-consistent renomalized (SCR) spin fluctuation theory for nearly AF metals, whereas below T<SUB>sf</SUB> a deviation is significant and 1/T<SUB>1</SUB>T exhibits a weak T variation. It is pointed out that T<SUB>sf</SUB> coincides with the temperature below which a T<SUP>2</SUP> law in electrical resistivlty is valid as expected for a Fermi liquid ground state. We proposed that these features are understood from the standpoint that the development of AF spin fluctuation remains in short-range associated with the singlet formation among Mn spins in each tetrahedron as suggested by the inelastic neutron experiments on Y<SUB>1-x</SUB>Sc<SUB>x</SUB>Mn<SUB>2</SUB>.
- The Review of High Pressure Science and Technology
The Review of High Pressure Science and Technology 7, 626-628, 1998
The Japan Society of High Pressure Science and Technology