NMR Studies of the Effect of Spin Fluctuations in Itinerant Electron Ferromagnet ZrZn₂

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Effects of external magnetic field and orbital degeneracy on the spin fluctuations in weakly ferromagnetic metals are studied based on the recent self-consistently renormalized spin fluctuation theory to obtain expressions for the spin fluctuation contributions to the nuclear magnetic relaxation rate 1/T₁ and the specific heat. By using these expressions and taking account of the orbital relaxation contribution, our experimental data of the temperature and magnetic field dependences of 1/T₁ for ⁹¹Zr in ZrZn₂ are well interpreted and are analysed semi-quantitatively yielding useful informations on the electronic structure of ZrZn₂. The spin fluctuation contribution to the specific heat at low temperatures in ZrZn₂ is also estimated.