Vortex dynamics in type-II superconductors under strong pinning conditions
Vortex dynamics in type-II superconductors under strong pinning conditions
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强钉扎条件下II型超导体的涡动力学
DOI：
10.1103/physrevb.96.144516
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发表时间：
2017
影响因子：
3.7
通讯作者：
G. Blatter
中科院分区：
文献类型：
--
作者：
A. U. Thomann;V. Geshkenbein;G. Blatter
我们研究了钉扎对第二类超导体中涡旋晶格动力学的影响，在强钉扎的情况下，结合解析和数值方法确定力-速度（或电流-电压）特性。我们的分析涉及一个小密度$n_p$的缺陷，与一个大的力$f_p$的旋涡作用，从而诱导的强钉扎理论的一个典型特征的配置。我们确定了与速度相关的平均钉扎力密度$\langle F_p（v）\rangle$，并发现它在速度标度$v_p \sim f_p/\eta a_0^3$上变化，其中$\eta$是涡运动的粘性，$a_0$是涡之间的距离。在小的针密度限制下，该速度远大于在临界力密度$F_c = \langle F_p（v=0）\rangle \propto n_p f_p$附近驱动的自由涡系统的典型流速$v_c \sim F_c/\eta$。其结果是，我们发现一个通用的过剩的力特性，一个几乎线性的力-速度特性的临界力密度$F_c$移动;线性通量流制度，只有在大型驱动器接近。我们的分析提供了一个推导库仑定律的干摩擦的情况下，强涡钉扎。
We study effects of pinning on the dynamics of a vortex lattice in a type II superconductor in the strong-pinning situation and determine the force--velocity (or current--voltage) characteristic combining analytical and numerical methods. Our analysis deals with a small density $n_p$ of defects that act with a large force $f_p$ on the vortices, thereby inducing bistable configurations that are a characteristic feature of strong pinning theory. We determine the velocity-dependent average pinning-force density $\langle F_p(v)\rangle$ and find that it changes on the velocity scale $v_p \sim f_p/\eta a_0^3$, where $\eta$ is the viscosity of vortex motion and $a_0$ the distance between vortices. In the small pin-density limit, this velocity is much larger than the typical flow velocity $v_c \sim F_c/\eta$ of the free vortex system at drives near the critical force-density $F_c = \langle F_p(v=0)\rangle \propto n_p f_p$. As a result, we find a generic excess-force characteristic, a nearly linear force--velocity characteristic shifted by the critical force-density $F_c$; the linear flux-flow regime is approached only at large drives. Our analysis provides a derivation of Coulomb's law of dry friction for the case of strong vortex pinning.