• DOI:10.1103/PHYSREVB.53.2815
• Corpus ID: 29922587

Vortex fluctuations and interlayer coupling in cuprates.

@article{Xue1996VortexFA,
  title={Vortex fluctuations and interlayer coupling in cuprates.},
  author={Xue and Cao and Xiong and Chen and Chu},
  journal={Physical review. B, Condensed matter},
  year={1996},
  volume={53 5},
  pages={
          2815-2818
        }
}

• Xue, Cao, +2 authors Chu
• Published 1 February 1996
• Physics
• Physical review. B, Condensed matter

It was observed 1 that all magnetization M(T) curves in cuprates at different H@Hcr cross at a temperature T* and M5M*, where M and Hcr are the reversible magnetization with H parallel to the c axis and a crossover field, respectively. Immediately after its discovery, this field-independent magnetization was taken as evidence for two-dimensional ~2D! vortex fluctuations. Experimental data further demonstrated that M* and T* serve as fundamental scales for M and T in the fluctuation regime. The data in a Bi2:2:1:2 sample 2 show that an additional term of 2TM * /T * in the expression ]M/] lnH5f 0/[32p 2 l ab (T)# of the London model is needed to account for the vortex-fluctuation effects, where f0 and lab are the flux quantum and the penetration depth in the a,b plane, respectively. The scaling fit of M in Bi2:2:2:3 ~Ref. 3! demonstrates that the ratio M/ M* is the proper dimensionless variable in the proposed scaling expression. It was also observed that the specific heat of Bi2:2:1:2 at various fields peaks at T*. 4 These observations led to much theoretical activity. The effects of vortex-configuration entropy were considered by Bulaevskii et al. ~the BLK model!. 5 There, a vortex line is treated as a stack of 2D vortex pancakes with an average separation of s, and is modeled as 2D classical particles of size apj ab , held through Josephson coupling, where jab and a are the coherence length in the a,b plane and a numerical parameter ;1, respectively. Decoupling of the pancakes occurs above a crossover field Hcr , and leads to an additional configuration-entropy term in the vortex free energy F, which is proportional to the density 1/s of the 2D pancake sheets. As a result, the derivative