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1. Tripling of the superconducting critical current density in BaFe ${}_2$ (As ${}_{1-x}$ P ${}_x$ ) ${}_2$ retained after pressure release

   https://doi.org/10.1088/1361-6668/ae702f  

   Liu, Jiangteng; Lopez, Alex; Slone, Daniel; Ren, Guodong; Liu, Zhaoyu; Idrobo, Juan-Carlos; Chu, Jiun-Haw; Eley, Serena (June 2026, Superconductor Science and Technology)

   Abstract Superconducting performance is tunable not only via chemical modification or defect engineering, but also through external parameters such as pressure, though this method remains less readily accessible. In this work, we study how compression influences vortex dynamics and critical currents in an iron-based superconductor. Specifically, we perform magnetization measurements using an off-the-shelf pressure cell to investigate the effects of hydrostatic pressures up to 1.08 GPa on the magnetic properties of BaFe ${}_2$(As ${}_{0.62}$P ${}_{0.38}$) ${}_2$crystals across a range of temperatures $T$and magnetic fields $H$. Although these pressures minimally affect the superconducting critical temperature, they produce a clear increase in the critical current density $J_{\mathrm{c}}(T,H)$, a pronounced reduction in the rate of thermally activated vortex motion $S(T,H)$, and can change the dominant vortex pinning mechanism. Furthermore, the effects of pressure are irreversible: after pressurization and subsequent release at room temperature, high-density microcracks are observed and the crystals retain their enhanced critical current densities. The second magnetization peak vanishes above 18 K after the pressure cycle, which we attribute to a transition from predominantly $\delta \kappa$pinning to a mixed mechanism of $\delta T_{\mathrm{c}}$and surface pinning. Lastly, a threefold increase in $J_{\mathrm{c}}$, a more than 40% reduction in $S$at 8 K and 0.5 T, and an expanded elastic-creep region were achieved after $1-2$pressure cycles. These findings demonstrate the potential utility of pressure cycling for improving $J_{\mathrm{c}}$, which may offer a simpler alternative compared to approaches such as chemical doping or the introduction of artificial pinning centers. 

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2. Absence of $E_{2g}$ Nematic Instability and Dominant $A_{1g}$ Response in the Kagome Metal ${\mathrm{CsV}}_3{\mathrm{Sb}}_5$

   https://doi.org/10.1103/PhysRevX.14.031015  

   Liu, Zhaoyu; Shi, Yue; Jiang, Qianni; Rosenberg, Elliott W; DeStefano, Jonathan M; Liu, Jinjin; Hu, Chaowei; Zhao, Yuzhou; Wang, Zhiwei; Yao, Yugui; et al (July 2024, Physical Review X)

   Ever since the discovery of the charge density wave (CDW) transition in the kagome metal ${\mathrm{CsV}}_3{\mathrm{Sb}}_5$, the nature of its symmetry breaking has been under intense debate. While evidence suggests that the rotational symmetry is already broken at the CDW transition temperature ( $T_{\mathrm{CDW}}$), an additional electronic nematic instability well below $T_{\mathrm{CDW}}$has been reported based on the diverging elastoresistivity coefficient in the anisotropic channel ( $m_{E_{2g}}$). Verifying the existence of a nematic transition below $T_{\mathrm{CDW}}$is not only critical for establishing the correct description of the CDW order parameter, but also important for understanding low-temperature superconductivity. Here, we report elastoresistivity measurements of ${\mathrm{CsV}}_3{\mathrm{Sb}}_5$using three different techniques probing both isotropic and anisotropic symmetry channels. Contrary to previous reports, we find the anisotropic elastoresistivity coefficient $m_{E_{2g}}$is temperature independent, except for a step jump at $T_{\mathrm{CDW}}$. The absence of nematic fluctuations is further substantiated by measurements of the elastocaloric effect, which show no enhancement associated with nematic susceptibility. On the other hand, the symmetric elastoresistivity coefficient $m_{A_{1g}}$increases below $T_{\mathrm{CDW}}$, reaching a peak value of 90 at $T^{*}=20\mathrm{K}$. Our results strongly indicate that the phase transition at $T^{*}$is not nematic in nature and the previously reported diverging elastoresistivity is due to the contamination from the $A_{1g}$channel. Published by the American Physical Society2024 

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3. Spreading resistance effects in tunneling spectroscopy of $\alpha \text{−}{\mathrm{RuCl}}_3$ and ${\mathrm{Ir}}_{0.5}{\mathrm{Ru}}_{0.5}{\mathrm{Cl}}_3$

   https://doi.org/10.1103/PhysRevB.108.245410  

   Frick, Jordan R; Sridhar, Samanvitha; Khansari, Ario; Comstock, Andrew H; Norman, Elizabeth; O’Donnell, Shaun; Maggard, Paul A; Sun, Dali; Dougherty, Daniel B (December 2023, Physical Review B)
4. Origin of the orbital polarization of ${\mathrm{Co}}^{2+}$ in ${\mathrm{La}}_2{\mathrm{CoTiO}}_6$ and ( ${\mathrm{LaCoO}}_3{)}_1+{\left({\mathrm{LaTiO}}_3\right)}_1$ : A $\mathrm{DFT}+U$ and DFMT study

   https://doi.org/10.1103/PhysRevB.103.125105  

   Lee, Alex Taekyung; Park, Hyowon; Ismail-Beigi, Sohrab (March 2021, Physical Review B)

   null (Ed.)
5. Raman scattering study of ${\mathrm{NaFe}}_{0.53}{\mathrm{Cu}}_{0.47}\mathrm{As}$

   https://doi.org/10.1103/PhysRevB.98.094512  

   Zhang, W.-L.; Song, Y.; Wang, W.-Y.; Cao, C.-D.; Dai, P.-C.; Jin, C.-Q.; Blumberg, G. (September 2018, Physical Review B)