Nd_2(Fe_(1-x)Co_x)_(14)B和Y_2(Fe_(1-x)Co_x)_(14)B的磁性

用磁测量和X-射线衍射研究了Nd_2(Fe_(1-x)Cox)_(14)B和Y_2(Fe_(1-x)Cox)_(14)B的晶格结构和内禀磁性。结果表明,低温下当钴含量较少时,Y_2(Fe_(1x)Cox)_(14)B的磁晶格向异性随钴含量的增加而增加,在1.5K和150K温度下,分别在x为0.4和0.2左右时磁晶各向异性常数达到极大;室温时的磁晶各向异性常数却随钴含量的增加而单调下降。用钴代换铁,对Nd_2(Fe_(1-x)Cox)_(14)B的自旋再取向温度的影响是复杂的。1.5K的饱和磁化强度在x=0.1左右达到极大。钴可以显著提高居里温度,对于Nd_2(Fe_(1-x)Cox)_(14)B和Y_2(Fe_(1-x)Cox)_(14)B,钴的作用几乎相同,表明居里温度主要由3d过渡金属原子之间的交换作用决定。     

THERMAL PROPERTIES OF KERR-NEWMAN-DE SITTER XY BLACK HOLES

Hawking radiation of scalar particles of Kerr-Newman-de Sitter XY (KNdSXY) black holes is studied by using complex analytical continuation (CAC) technique. We derive the surface gravity κ_h,κ_c and Hawking temperature T_b,T_c of the event horizons r₊,r₊₊. All of them are proportional to (|A|)^1/2, where A is an indefinite multiple of KNdSXY metric.     

ASYMPTOTIC EXPANSION OF GREEN FUNCTION OR HEAT KERNEL IN SPACE WITH TORSION

An algorithm for asymptotic expansion of Green function or heat kemel in space with torsion is proposed. The De Witt-Seeley-Gilkey coeffcient E₂(x) is calculated.