Calorimetric measurement of the latent heat of vortex-lattice melting in untwinned YBa2Cu3O7–δ

Melting of the vortex lattice in high−Tcsuperconductors

“…As an example, on Fig.2 we present the fitting of the melting line of fully oxidized Y Ba 2 Cu 3 O 7 [7] which gives T c = 88.2, H c2 = 175.9, Gi = 7.0 10 −5 , κ = 50. Melting lines of optimally doped untwinned [3] Y Ba 2 Cu 3 O 7−δ and DyBa 2 Cu 3 O 7 [26] are also fitted extremely well. For example, for Y Ba 2 Cu 3 O 7−δ in [3], the melting line fitting gives T c = 93.07, H c2 = 167.53, Gi = 1.9 10 −4 , κ = 48.5 (see also ref.…”

“…In high T c cuprates at relatively high temperatures, vortices move and vibrate due to thermal fluctuations to the extent that the lattice can melt becoming a "vortex liquid" [1]. Several recent remarkable experiments clearly determined that the vortex lattice melting in high T c superconductors is a first order phase transition with magnetization jumps [2] and spikes in specific heat [3]. The magnetization and entropy jumps were measured using diverse techniques such as local Hall probes, SQUID [4,5], torque magnetometry [6,7] and integration of the specific heat spike [3].…”

“…The magnetization and entropy jumps were measured using diverse techniques such as local Hall probes, SQUID [4,5], torque magnetometry [6,7] and integration of the specific heat spike [3]. Related investigations indicate that, in addition to the spike, there is also a jump in specific heat [3,8]. In spite of those precise measurements of vortex melting, a quantitative theoretical description of vortex melting is still lacking.…”

“…Several recent remarkable experiments clearly determined that the vortex lattice melting in high T c superconductors is a first order phase transition with magnetization jumps [2] and spikes in specific heat [3]. The magnetization and entropy jumps were measured using diverse techniques such as local Hall probes, SQUID [4,5], torque magnetometry [6,7] and integration of the specific heat spike [3]. Related investigations indicate that, in addition to the spike, there is also a jump in specific heat [3,8].…”

Current-driven vortex dynamics in untwinned superconducting single crystals

“…Recent experimental observations of novel vortex transport properties in various weakpinning type-II superconductors [1][2][3][4][5][6][7][8][9][10] have kindled renewed interest in the effects of static disorder on the thermodynamic vortex phases and phase transitions [11][12][13][14][15][16]. In the weak-pinning limit, measurements of thermodynamic quantities such as magnetization and heat capacity have confirmed the existence of a first-order melting transition in both Bi 2 Sr 2 CaCu 2 O x [9] and untwinned YBa 2 Cu 3 O 7 single crystals [10], while the resistive hysteresis observed in untwinned YBa 2 Cu 3 O 7 single crystals below the first-order vortexsolid melting transition temperature T M [1][2][3] has been attributed to the current-driven non-equilibrium effects below the thermodynamic transition [3].…”