Magnetic-susceptibility anisotropy of single-crystal Bi2Sr2CaCu2O8

Crystal orientation and crystal structure of paramagnetic α-Al under a pulsed electromagnetic field

The intermittent electromagnetic fields with a large \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\partial \mathrm{B}/\partial \mathrm{t}$$\end{document}∂B/∂t can enhance the properties of ferromagnetic materials and significantly affect paramagnetic materials. In this study, the effect of a pulsed electromagnetic field on the crystal orientation of the primary phase and microstructure evolution of an Al–Zn–Mg–Cu alloy was investigated. A mathematical model was developed to describe crystal rotation under a pulsed electromagnetic field. The model predictions show that the magnetic energy difference generated by the magnetic anisotropy of the primary crystal produces primary phases with sizes of 225–100 μm to rotate into a <111> preferred orientation. The lattice constant, the interplanar spacing, and the microstrain increase with the duty cycle of the pulsed magnetic field, especially for the (111) and (200) crystal planes. This study provides preliminary theoretical support for using pulsed electromagnetic fields to control the orientation and microscopic properties of materials.

Superconducting and normal-state anisotropy of the doped topological insulator Sr0.1Bi2Se3

Sr_xBi₂Se₃ and the related compounds Cu_xBi₂Se₃ and Nb_xBi₂Se₃ have attracted considerable interest, as these materials may be realizations of unconventional topological superconductors. Superconductivity with T_c ~3 K in Sr_xBi₂Se₃ arises upon intercalation of Sr into the layered topological insulator Bi₂Se₃. Here we elucidate the anisotropy of the normal and superconducting state of Sr_0.1Bi₂Se₃ with angular dependent magnetotransport and thermodynamic measurements. High resolution x-ray diffraction studies underline the high crystalline quality of the samples. We demonstrate that the normal state electronic and magnetic properties of Sr_0.1Bi₂Se₃ are isotropic in the basal plane while we observe a large two-fold in-plane anisotropy of the upper critical field in the superconducting state. Our results support the recently proposed odd-parity nematic state characterized by a nodal gap of Eu symmetry in Sr_xBi₂Se₃.

Field-enhanced diamagnetism in the pseudogap state of the cuprate Bi2Sr2CaCu2O(8+delta) superconductor in an intense magnetic field

In hole-doped cuprates, Nernst experiments imply that the superconducting state is destroyed by spontaneous creation of vortices which destroy phase coherence. Using torque magnetometry on Bi2Sr2CaCu2O(8+delta), we uncover a field-enhanced diamagnetic signal M above the transition temperature Tc that increases with applied field to 32 Tesla and scales just like the Nernst signal. The magnetization results above Tc distinguish M from conventional amplitude fluctuations and strongly support the vortex scenario for the loss of phase coherence at Tc.

Pseudogap in Bi2Sr2CaCu2O8+delta studied by measuring anisotropic susceptibilities and out-of-plane transport

We find in the Bi2Sr2CaCu2O8+delta system that the characteristic temperatures T*chi [below which the uniform susceptibilities chiabT (Hperpendicularc) and chicT (Hparallelc) decrease] and T*(rhoc) [below which the out-of-plane resistivity rhoc(T) shows typical upturn] coincide for all doping levels. We attribute the T dependence of chi's and rhoc to the anomalous (pseudogapped) density of states (DOS) in high- Tc cuprates. Furthermore, the anisotropy in the T dependence of chi's is universal, i.e., chic approximately 1.6chiab, showing that there is only a single T-dependent component in the chi's. This implies that the Curie-like behavior (dchi/dT<0) observed in overdoped samples is also caused by a DOS effect.