arXiv subjects

Priti Yadav

Publications and source records attributed to Priti Yadav.

3 recordsLinked to original sources

arXiv2026

Element-Specific Visualization of Layer-Parity and Twist-Dependent Magnetism in CrSBr

Van der Waals (vdW) based antiferromagnets (AFMs) are an ideal platform for probing and understanding thickness- and twist-angle-dependent emergent spin phenomena. However, element-specific nanoscale characterization of the spin structure in atomically thin vdW-based AFMs systems and layer-parity effects remain elusive, making them crucial for both fundamental insight into low-dimensional magnetism and the rational design of spintronic devices based on these materials. Here, we utilize X-ray magnetic circular and linear dichroisms paired with photoemission electron microscopy to resolve the magnetic order in atomically thin CrSBr. Our comprehensive measurements reveal CrSBr magnetic structure at the nanoscale and its dependence on the layer number, surface encapsulation, temperature, and applied field. Moreover, in the orthogonally twisted bilayer configuration, obtained by twisting two CrSBr ferromagnetic monolayers by 90$^\circ$, the magnetic easy axis fundamentally differs from the individual monolayers, unlocking a new pathway for moir\'e magnetism.

cond-mat.mes-hall↗

arXiv2026

Visualizing Nanoscopic Acoustic Mode Competition in van der Waals Ferroelectric

Understanding how low-dimensional ferroelectrics respond to ultrafast excitation at nanoscales is essential for controlling energy flow and mechanical functionality in next-generation polar devices, yet the nanoscopic structural response to ultrafast depolarization remains unresolved, obscuring the microscopic pathways of acoustic decoherence and energy dissipation. Here, we spatiotemporally resolve lattice motion in the van der Waals ferroelectric NbOI2 using combined ultrafast electron microscopy and diffraction, revealing three acoustic phonons: two transverse shear modes and one longitudinal breathing mode. The transverse mode that shears the layers perpendicular to the in-plane polar axis dominates over that along the polar axis, reflecting anisotropic polarization-strain coupling. Real-space mapping uncovers spatially correlated heterogeneity in mode amplitudes and lifetimes. Regions dominated by a single shear mode exhibit significantly longer acoustic lifetimes than multimode regions, suggesting acoustic phonon-phonon scattering as a major source of decoherence. Our results provide a microscopic understanding of ultrafast depolarization-driven acoustic dynamics and spatially heterogeneous energy dissipation in van der Waals ferroelectrics.

cond-mat.mtrl-sci↗

arXiv2025

Atomic-scale spin sensing of a 2D $d$-wave altermagnet via helical tunneling

Altermagnetism simultaneously possesses nonrelativistic spin responses and zero net magnetization, thus combining advantages of ferromagnetism and antiferromagnetism. This superiority originates from its unique dual feature, i.e., opposite-magnetic sublattices in real space and alternating spin polarization in momentum space enforced by the same crystal symmetry. Therefore, the determination of an altermagnetic order and its unique spin response inherently necessitates atomic-scale spin-resolved measurements in real and momentum spaces, an experimental milestone yet to be achieved. Here, via utilizing the helical edge (hinge) modes of a higher order topological insulator as the spin sensor, we realize spin-resolved scanning tunneling microscopy which enables us to pin down the dual-space feature of a layered $d$-wave altermagnet, KV$_2$Se$_2$O. In real space, atomic-registered mapping demonstrates the checkerboard antiferromagnetic order together with density-wave lattice modulation, and in momentum space, spin-resolved spectroscopic imaging provides a direct visualization of d-wave spin splitting of the band structure. Critically, using this new topology-guaranteed spin filter we directly reveal the unidirectional, spin-polarized quasiparticle excitations originating from the crystal symmetry-paired X and Y valleys around opposite magnetic sublattices simultaneously --the unique spin response for $d$-wave altermagnetism. Our experiments establish a solid basis for the exploration and utilization of altermagnetism in layered materials and further facilitate access to atomic-scale spin sensing and manipulating of 2D quantum materials.

cond-mat.mes-hall↗