arXiv subjects

Shams Sohel Islam

Publications and source records attributed to Shams Sohel Islam.

3 recordsLinked to original sources

arXiv2026

Lifting the degeneracy of quantum spin liquid phase by uniaxial pressure

We report muon spin relaxation/rotation ($μ$SR) measurements of the candidate three-dimensional (3D) quantum spin liquid (QSL) PbCuTe$_2$O$_6$, hosting $S=1/2$ moments, under controlled in situ [110] uniaxial compression up to $σ_{[110]}=37.7$~MPa. A small directional lattice perturbation significantly modifies the local magnetic response, while above $σ_{\rm cr}\sim10.8$\,MPa the relaxation rates are strongly enhanced and the internal-field distribution is substantially broadened. These changes occur along with the local crystalline symmetry breaking. While, no evidence for conventional static long-range magnetic order is observed, the compression drives the system towards a structurally modified and strongly correlated state in which enhanced quasi-static correlations coexist with persistent slow spin dynamics. This work demonstrates a clean and symmetry-selective route to control frustrated exchange landscape and access hidden magnetic instabilities in a 3D QSL candidate opening up the possibilities to tune other correlated systems where intrinsic coupling between magnetic and lattice degrees of freedom are relevant.

cond-mat.str-el↗

arXiv2026

Emergence of a Fluctuating Ground State in Y-kapellasite under Pressure

Y-kapellasite (Y$_3$Cu$_9$(OH)$_{19}$Cl$_8$), which hosts an original anisotropic kagome sublattice, is a promising candidate for studying elusive and complex correlated physics. It exhibits a theoretically predicted in-plane $(1/3, 1/3)$ magnetic order [1] but its magnetic interaction values place it close to a phase boundary to a spin liquid state [2]. Our $μ$SR measurements under hydrostatic pressure demonstrate the complete suppression of static magnetism in favor of a fully dynamical ground state at $2.3$~GPa. Complementary high-pressure x-ray and optical phonon measurements reveal a gradual reduction of the kagome anisotropy, enhancing magnetic frustration without structural transitions. Our results establish Y-kapellasite as a rare clean kagome model in which long-range order is suppressed by pressure-tuned frustration, the first fingerprint for the realization of a quantum spin liquid without strong disorder.

cond-mat.str-el↗

arXiv2026

Non-collinear ferromagnetism in the Kondo lattice Ce$_5$CoGe$_2$

The dense Kondo lattice Ce$_5$CoGe$_2$ exhibits superconductivity once the magnetic ordering is suppressed by pressure. Here the ambient pressure magnetic state is investigated via magnetization, heat capacity, powder neutron diffraction, and muon spin relaxation ($μ$SR) measurements. Neutron diffraction results reveal a noncollinear ferromagnetic structure, where the four inequivalent Ce sites exhibit different magnetic moments. Point-charge model calculations of the crystalline-electric field (CEF) ground states corroborate different moments between the sites, and suggest sizeable components of the moments along different directions, consistent with the non-collinear structure. Analysis of the Dzyaloshinskii-Moriya (DM) interaction for the bonds connecting Ce atoms demonstrates that most of these bonds exhibit a nonzero DM vector, suggesting that competition between intersite magnetic exchange interactions, CEF driven single-ion anisotropy, the Kondo effect and the DM interaction may drive the non-collinear ferromagnetism.

cond-mat.str-el↗