Interlayer Phase Coherence in the Vortex Matter Phases ofBi2Sr2CaCu

Abstract

The interlayer phase coherence in Bi 2 Sr 2 CaCu 2 O 81y was quantitatively determined in a wide field range by using the Josephson plasma resonance (JPR). At the first-order transition (FOT), a novel frequency-independent JPR with sharp resonance width is found, indicating a jump in the interlayer phase coherence. Above the FOT, sample-moving magnetization measurements show an anomaly consistent with the report by Fuchs et al. [Phys. Rev. Lett. 80, 4971 (1998)], where the interlayer phase coherence shows no anomaly. These results suggest the decoupling nature of the FOT, and can rule out the existence of the vortex line liquid state.

Phase diagram of vortices in high-Tcsuperconductors with a melting line in the deepHc2region

“…1 a possible additional phase boundary labeled by T x which was found by Fuchs et al [20] by measuring the vortex penetration through surface barriers. A similar line was also found by magnetization measurements [21]. This line divides the vortex liquid denoted by VL from the phase VG1 shown in Fig.…”

“…In contrast to YBCO, BSCCO is a strongly layered material where the coupling between the layers is described by the Josephson coupling in the Hamiltonian of the system. For high magnetic fields beyond the first-order line, one obtains a suppression of the Josephson coupling between the layers [21,29] with respect to the electromagnetic coupling. In our elastic model with defects, we can not get this decoupling.…”

“…It was shown in Ref. [21] via Josephson plasma experiments that the T x -line is not accompanied by a Josephson decoupling between the layers ruling out the possibility of a transition from vortex lines to weakly coupled pancake vortices. That such a transition exist was proposed theoretically in Refs.…”

Effects of Point Defects on the Phase Diagram of Vortex States in High-TcSuperconductors in theB‖Nonomura1, Hu2 2001Phys. Rev. Lett.787741View full textAdd to dashboardCite

“…[35] In such a case, it might be difficult to observe a jump of cos(φ n − φ n+1 ) outside of the BG phase by the JPR. [39,37] Finally, the present results summarized in Fig. 1 are compared with theoretical studies related to the VS phase in literature.…”

“…[37] Discussions.-On the melting line of pure systems, ∆ cos is proportional to Γ 2 f and gradually approaches a saturated value, [38] ∆ cos ≈ 0.3. [39,35] When the anisotropy is as small as that of YBCO (Γ ≈ 7 ∼ 8), ∆ cos is small both on the melting line and on the BG-VG phase boundary. In the present system (Γ = 20), ∆ cos (≈ 0.22 at ǫ = 0.05) is as large as the saturated value on the melting line, while it is small on the BG-VG/VS phase boundary.…”