Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
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Tham khảo tài liệu 'superconductivity theory and applications part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Coherent Current States in Two-Band Superconductors 39 two- and one- band superconductors have been studied recently in a number of articles Agterberg et al. 2002 Ota et al. 2009 Ng Nagaosa 2009 . Another basic type of Josephson junctions are the junctions with direct conductivity S-C-S contacts C -constriction . As was shown in Kulik Omelyanchouk 1975 Kulik Omelyanchouk 1978 Artemenko et al. 1979 the Josephson behavior of S-C-S structures qualitatively differs from the properties of tunnel junctions. A simple theory analog of Aslamazov-Larkin theory Aslamazov Larkin 1968 of stationary Josephson effect in S-C-S point contacts for the case of two-band superconductors is described in Sec.4 . 2. Ginzburg-Landau equations for two-band superconductivity. The phenomenological Ginzburg-Landau GL free energy density functional for two coupled superconducting order parameters I1 and I2 can be written as H2 FGL F1 F2 F12 Where F1 1 1 2 1P1 1 4 T7K 2 2m1 I1 F2 a2 I1 Pl 1 21 o 2 2m2 I2 1 2 and f - .Í. . . 12 -rwh Ar 2e -1 2e -1 - I -ÌHV- A I1 in - A I2 V c V c 2e -1 . 2e -1 I irn- A l I -iW- A l 2 V c J k c J 3 The terms F1 and F2 are conventional contributions from I and 2 term F12 describes without the loss of generality the interband coupling of order parameters. The coefficients Ỵ and r describe the coupling of two order parameters proximity effect and their gradients drag effect Askerzade 2003a Askerzade 2003b Doh et al. 1999 respectively. The microscopic theory for two-band superconductors Koshelev Golubov 2003 Zhitomirsky Dao 2004 Gurevich 2007 relates the phenomenological parameters to microscopic characteristics of superconducting state. Thus in clean multiband systems the drag coupling term r is vanished. Also on phenomenological level there is an important 1 condition that absolute minimum of free GL energy exist ir . see Yerin et al. 2 1 m1m2 2008 . 40 Superconductivity - Theory and Applications By minimization the free energy F I F1 F2 F12 d3r with respect toi q ự
