Intrinsic pinning and guided motion of vortices in high-Tc superconductors

Physica C: Superconductivity

2003

This article is devoted to the problem of the validity of the reciprocity theorem in high-temperature superconductors (HTSC). The violation of the reciprocity theorem in zero external magnetic fields has been studied. Experimental data obtained for two different superconducting materials: BiSrCaCuO and YBaCuO are presented. Results show that the basic form of the reciprocity theorem (without consideration of any additional anisotropy) is not valid near the critical temperature. We assume that the reciprocity theorem breaking is connected with the existence of an extraordinary transverse electric field originated from additional anisotropy and more general form of the reciprocity relations should be valid. However, the origin of this anisotropy is not clear yet. We suggest that the vortex-antivortex dynamics model taking into account vortex guiding can be responsible for the observed effect. Also the explanation based on weak P and T symmetry breaking in HTSC which is supported by the observation of the spontaneous magnetisation can not be excluded.Comment: 15 pages, 11 figure

Section: Discussionmentioning

confidence: 99%

Reciprocity theorem in high-temperature superconductors

Janeček

Physica C: Superconductivity

2003

“…Thus, the probability that vortex on the left meets antivortex on the right-hand side is equal to the probability of the opposite event, from whence mean transverse voltage is zero. However, a non-zero voltage can be observed, when these induced vortices are moving under influence of any force which violates vortex-antivortex symmetry (for example guiding force [11] etc.). But vortices can be generated in the sample in the absence of the external magnetic field also by another way.…”

Section: Resultsmentioning

confidence: 99%

Transverse voltage in zero external magnetic fields, its scaling and violation of the time-reversal symmetry in MgB2

Physica C: Superconductivity and its Applications

Shimakage

Wang

2004

Self Cite

The longitudinal and transverse voltages (resistances) have been measured for MgB 2 in zero external magnetic fields. Samples were prepared in the form of thin film and patterned into the usual Hall bar shape. In close vicinity of the critical temperature T c non-zero transverse resistance has been observed. Its dependence on the transport current has been also studied. New scaling between transverse and longitudinal resistivities has been observed in the form ρ xy ∼ dρ xx /dT . Several models for explanation of the observed transverse resistances and breaking of reciprocity theorem are discussed. One of the most promising explanation is based on the idea of time-reversal symmetry violation.

“…With the increasing magnetic field the even voltage is suppressed. Usually accepted explanation of the even effect is the existence of guided motion of vortices [14]. In this case the vortices which are present in the sample under study are force to move not in direction of the Lorentz force but in some channels .…”

Section: Methodsmentioning

confidence: 99%

Transport in MgB₂ near critical temperature

Phys. Status Solidi (c)

2006

Self Cite

Longitudinal and transverse voltages have been studied on samples of MgB 2 . The non-zero transverse voltage has been observed in close vicinity of critical temperature in zero external magnetic field while far enough from Tc this voltage has been zero. It merges into transverse even voltage in magnetic field which is suppressed with increasing field and increasing transport current as well. New scaling between transverse and longitudinal resistivities has been observed in the form ρ xy ~ dρ xx /dT. Several models trying to explain observed results are discussed.