Anisotropy of the Sommerfeld coefficient in magnesium diboride single crystals

作者：Pribulova Z^*; Klein T; Marcus J; Marcenat C; Levy F; Park M S; Lee H G; Kang B W; Lee S I; Tajima S; Lee S

来源：Physical Review Letters, 2007, 98(13): 137001.

DOI：10.1103/PhysRevLett.98.137001

The anisotropic field dependence of the Sommerfeld coefficient gamma has been measured down to B -> 0 by combining specific heat and Hall probe magnetization measurements in MgB2 single crystals. We find that gamma(B,theta) is the sum of two contributions arising from the sigma and pi band, respectively. We show that gamma(sigma)(B,theta)=B/B-c2(theta) where B-c2(theta)=B-c2(ab)/root sin(2)theta+Gamma(2)cos(2)theta with Gamma similar to 5.4 (theta being the angle between the applied field and the c axis) and gamma(pi)(B,theta)=gamma(pi)(B)=B/B-pi(B). The "critical field" of the pi band B-pi is fully isotropic but field dependent increasing from similar to 0.25 T for B <= 0.1 T up t

• 出版日期2007-3-30
• 单位中国地震局