Flux-line lock-in to CuO planes in aLa1.9Sr0.1CuO4

Abstract

We report on vector magnetization studies of a La 1.9 Sr 0.1 CuO 4 single crystal, cut in the form of a disk with the anisotropy (c) axis parallel to the disk plane. We observe a sharp threshold in the angular dependences of the isothermal remanent magnetization. When the magnetic field is applied within a threshold angle to the ab plane, the remanent moment is strictly parallel to ab, and also the c-axis component of magnetization is reversible. The threshold angle scales with temperature in the same manner as the lower critical field parallel to the c axis, H c1 c . These observations give direct support to the presence of a vortex lock-in transition to the CuO planes in our crystal. ͓S0163-1829͑97͒06733-7͔

Observation of lock-in phenomena in heavy-ion-irradiated single crystal ofBa(Fe0.93Co0.07)2Taen1, Yagyuda2, Nakajima3 et al. 2014Phys. Rev. B6041View full textAdd to dashboardCite

“…When H is tilted away from the direction of the CDs by an angle smaller than the so-called lock-in angle (θ L ), the vortices remain trapped by the CDs in their whole length. This stiffness of the vortex configuration manifests as an almost orientation-independent J c over the angular extension of the lock-in phenomenon, which has often been observed in oxide HTS in magnetization [11][12][13][14][15] and transport measurements [16][17][18]. However, until now this second fingerprint of correlated pinning had not been observed in IBSs.…”

Evidence of two-dimensional Josephson strings in high-purityYBa2Cu3ODeligiannis1, Kokkaliaris2, Oussena3 et al. 1999Phys. Rev. B6100View full textAdd to dashboardCite

“…4 On the other hand, careful transport measurements in YBa 2 Cu 3 O 7Ϫ␦ exhibited an abrupt, impressive drop of resistivity for fields applied in the ab plane and flux motion geometry vertical to the layers, 5,6 due to intrinsic pinning. Elegant vector magnetization measurements 7,8 proved also to be useful in detecting the lock-in transition, by monitoring the accompanying transverse Meissner effect.…”

“…Furthermore, in interpreting a transverse Meissner effect one has to be aware of possible electrodynamic and not thermodynamic ͑vortex lock-in͒ origins. 8 In any case, these techniques, for different reasons, are not in a position to enlighten us about the behavior of the 2D Josephson strings system or verify the existing theories for the vortex lattice structure and behavior in the quasi-2D regime.…”

Magnetic flux rotation anomalies in superconductingLa1.85Sr0.15CuO4

“…3,7,9,22,23 In this paper, we report on anomalous behavior of the onset field H * for flux rotation, previously overlooked in studies of the lock-in effect in La 1.85 Sr 0.15 CuO 4 ͑LSCO͒ crystals. 11,12 Namely, we find that H * exhibits a power-law dependence upon the tilting angle with a sharp jump in the exponent around 15 K. Also, the temperature dependence of H * , measured for a constant tilting angle, exhibits a pronounced peak around the same temperature. In addition, the behavior of the remnant magnetization vector M R , after turning off a tilted field, also changes around T * : M R rotates toward the c axis at low temperatures crossing over to rotation toward the ab plane at high temperatures.…”

“…1-21 Among them is the so-called "lock-in" effect 3 observed when a small external field is applied at a small angle H to the ab planes. It was predicted theoretically 3,7,9 and observed experimentally 4, 6,8,11,12 that there is a finite lock-in angle c , such that when H Ͻ c , the flux lines run parallel to the planes, remaining "locked in" between the layers. When either the applied field or the tilting angle exceeds their critical value, the flux starts rotating toward the direction of the external field forming an array of kinked vortices.…”