First-order phase transition of the vortex lattice in twinned YBa 2 Cu 3 O 7 single crystals in tilted magnetic fields
First-order phase transition of the vortex lattice in twinned YBa 2 Cu 3 O 7 single crystals in tilted magnetic fields
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倾斜磁场中孪生YBa 2 Cu 3 O 7 单晶涡旋晶格的一级相变
DOI：
10.1103/physrevb.61.12427
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
E. Osquiguil
中科院分区：
文献类型：
--
作者：
B. Maiorov;G. Nieva;E. Osquiguil
我们对孪生 ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}$ 单晶中进行的输运测量进行了详尽的分析，确定当磁场 H 以远离孪生平面方向的角度 $\ensuremath{\theta}$ 施加时，涡流固液转变为一阶。我们证明电阻转变是滞后的，并且 $V\ensuremath{-}I$ 曲线是非线性的，在熔线 ${H}_{m}(T),$ 处显示特征 S 形状，其比例为 $\ensuremath{\varepsilon}(\ensuremath{\theta}{)H}_{m}(T,\ensuremath{\theta}),$ 其中$\ensuremath{\varepsilon}(\ensuremath{\theta})$ 是各向异性因子。当接近临界点${H}^{*}(\ensuremath{\theta})$时，这些特征逐渐丢失。在 ${H}^{*}(\ensuremath{\theta})$ 之上，$V\ensuremath{-}I$ 特性在实验上可访问的 $V\ensuremath{-}I$ 窗口中显示出线性响应，并且转变变得可逆。最后，我们证明一阶相变发生在场方向上高度相关的涡旋液体和未知对称性的固态之间。因此，我们的数据支持孪生 ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}$ 晶体中涡旋线熔化的情况，而不是最近建议的非孪生晶体的涡旋升华${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4},{\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}$ 和${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8}$ [T.笹川等人，物理学。莱特牧师。 80 美元，4297 美元（1998 年）]。
We present an exhaustive analysis of transport measurements performed in twinned ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}$ single crystals which establishes that the vortex solid-liquid transition is first order when the magnetic field H is applied at an angle $\ensuremath{\theta}$ away from the direction of the twin planes. We show that the resistive transitions are hysteretic and the $V\ensuremath{-}I$ curves are nonlinear, displaying a characteristic S shape at the melting line ${H}_{m}(T),$ which scales as $\ensuremath{\varepsilon}(\ensuremath{\theta}{)H}_{m}(T,\ensuremath{\theta}),$ where $\ensuremath{\varepsilon}(\ensuremath{\theta})$ is the anisotropy factor. These features are gradually lost when the critical point ${H}^{*}(\ensuremath{\theta})$ is approached. Above ${H}^{*}(\ensuremath{\theta})$ the $V\ensuremath{-}I$ characteristics show a linear response in the experimentally accessible $V\ensuremath{-}I$ window, and the transition becomes reversible. Finally we show that the first-order phase transition takes place between a highly correlated vortex liquid in the field direction and a solid state of unknown symmetry. As a consequence, our data support the scenario for a vortex-line melting in twinned ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}$ crystals in contrast to a vortex sublimation as recently suggested for untwinned ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4},{\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}$ and ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8}$ [T. Sasagawa et al., Phys. Rev. Lett. $80,$ 4297 (1998)].