Quantum magnetic short-range order in the paramagnetic state

A specific quantum magnetic short-range order above the critical temperature for ferromagnets is identified and analyzed. Using quantum Heisenberg model calculations with various exchange interactions parameters of different spins, we found that the quantum spin effect significantly contribute to the magnetic short-range order at rather high temperatures. For a system of small spins such a large short-range order can appear without the abnormal susceptibility which has been previously reported. The influence of this quantum effect on the critical temperature and spin wave spectrum will be discussed. We have also studied the fluctuations of the magnitude of the magnetic moment, and believe that they can also be responsible for the observed Curie-Weiss behavior of the susceptibility above the Curie temperature in real metals.