Study of paramagnetic phase of metallic magnet by means of microscopic methods

对一系列准二元金属间化合物Y(Mn_&lt；1-x&gt；Al_x)_2进行了弹性和非弹性中子散射测量。在T_N-100K以下，只有5%的锰原子被铝原子取代，YMn_2中的长程反铁磁有序就瓦解了。在这些化合物中，散射中子谱的能量宽度的变化以及磁化率测量中的场滞后的开始，都清楚地表明了自旋玻璃转变。在x=0.10的化合物中，S的自旋涨落幅度随温度变化不大，而在YMn2中，在T_N时，自旋涨落幅度下降了30%以上，然后随着温度的升高逐渐增大。相当程度的自旋涨落空间关联至少持续到760K，这类似于在YMn2中观察到的行为，但与简单定域电子磁体的特征有很大的不同。

Elastic and inelastic neutron scattering measurements have been made on a series of pseudobinary intermetallic compounds Y(Mn_<1-x>Al_x)_2. Long range antiferronagnetic order below T_N - 100K in YMn_2 has been shown to collapse by substitution of only 5% of the manganese atoms by aluminum atoms. In these compounds, a spin glass transition has been clearly indicated by a change in the energy width of the scattered neutron spectrum, as well as by the onset of field hysteresis in susceptibility measurements. In the compound with x = 0.10, the amplitude of spin fluctuations S does not change appreciably with temperature, whereas in YMn_2 it drops by more than 30% at T_N and then increases gradually with increasing temperature. A considerable degree of spatial correlations of spin fluctuations persists up to at least 760K, which is similar to the behavior observed in YMn_2 but quite different from the characteristics of simple localized electron magnets.