Browsing by Author "Khasanov, R."

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    Gradual enhancement of stripe-type antiferromagnetism in the spin-ladder material BaFe2S3 under pressure
    (American Physical Society, 2018) Zheng, Liangliang; Frandsen, Benjamin A.; Wu, Changwei; Yi, Ming; Wu, Shan; Huang, Qingzhen; Bourret-Courchesne, Edith; Simutis, G.; Khasanov, R.; Yao, Dao-Xin; Wang, Meng; Birgeneau, Robert J.
    We report pressure-dependent neutron diffraction and muon spin relaxation/rotation measurements combined with first-principles calculations to investigate the structural, magnetic, and electronic properties of BaFe2S3 under pressure. The experimental results reveal a gradual enhancement of the stripe-type ordering temperature with increasing pressure up to 2.6 GPa and no observable change in the size of the ordered moment. The ab initio calculations suggest that the magnetism is highly sensitive to the Fe-S bond lengths and angles, clarifying discrepancies with previously published results. In contrast to our experimental observations, the calculations predict a monotonic reduction of the ordered moment with pressure. We suggest that the robustness of the stripe-type antiferromagnetism is due to strong electron correlations not fully considered in the calculations.
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    Tunable unconventional kagome superconductivity in charge ordered RbV3Sb5 and KV3Sb5
    (Springer Nature, 2023) Guguchia, Z.; Mielke, C.; Das, D.; Gupta, R.; Yin, J.-X.; Liu, H.; Yin, Q.; Christensen, M.H.; Tu, Z.; Gong, C.; Shumiya, N.; Hossain, Md Shafayat; Gamsakhurdashvili, Ts; Elender, M.; Dai, Pengcheng; Amato, A.; Shi, Y.; Lei, H.C.; Fernandes, R.M.; Hasan, M.Z.; Luetkens, H.; Khasanov, R.
    Unconventional superconductors often feature competing orders, small superfluid density, and nodal electronic pairing. While unusual superconductivity has been proposed in the kagome metals AV3Sb5, key spectroscopic evidence has remained elusive. Here we utilize pressure-tuned and ultra-low temperature muon spin spectroscopy to uncover the unconventional nature of superconductivity in RbV3Sb5 and KV3Sb5. At ambient pressure, we observed time-reversal symmetry breaking charge order below $${T}_{{{{{{{{\rm{1}}}}}}}}}^{*}\simeq$$110 K in RbV3Sb5 with an additional transition at $${T}_{{{{{{{{\rm{2}}}}}}}}}^{*}\simeq$$50 K. Remarkably, the superconducting state displays a nodal energy gap and a reduced superfluid density, which can be attributed to the competition with the charge order. Upon applying pressure, the charge-order transitions are suppressed, the superfluid density increases, and the superconducting state progressively evolves from nodal to nodeless. Once optimal superconductivity is achieved, we find a superconducting pairing state that is not only fully gapped, but also spontaneously breaks time-reversal symmetry. Our results point to unprecedented tunable nodal kagome superconductivity competing with time-reversal symmetry-breaking charge order and offer unique insights into the nature of the pairing state.