arXiv subjects

P. Laurell

Publications and source records attributed to P. Laurell.

4 recordsLinked to original sources

arXiv2026

Nonlinear light cone spreading of correlations in a triangular quantum magnet: a hard quantum simulation target

Dynamical correlations of quantum many-body systems are typically analyzed in the momentum space and frequency basis. However, quantum simulators operate more naturally in real space, real time settings. Here we analyze the real-space time-dependent van Hove spin correlations $G(r,t)$ of the 2D triangular antiferromagnet KYbSe$_2$ as obtained from high-resolution Fourier-transformed neutron spectroscopy. We compare this to $G(r,t)$ from five theoretical simulations of the well-established spin Hamiltonian. Our analysis reveals non-linear sub-ballistic low-temperature transport in KYbSe$_2$ which none of the current state-of-the-art numerical or field-theoretical methods reproduce. Our observation signals an emergent collective hydrodynamics, perhaps associated with the quantum critical phase of a quantum spin liquid, and provides an ideal benchmark for future quantum simulations.

cond-mat.str-el↗

arXiv2025

Cooper-Pair Localization in the Magnetic Dynamics of a Cuprate Ladder

We investigate the spin dynamics of the cuprate ladder Sr$_{2.5}$Ca$_{11.5}$Cu$_{24}$O$_{41}$ to elucidate the behavior of its intrinsically doped holes. Combining high-resolution neutron spectroscopy and density matrix renormalization group calculations enables a comprehensive analysis of the collective magnetic dynamics. We find a general absence of magnetic signatures from unpaired charges, indicating holes within the system form strongly bound localized Cooper pairs. A one-band Hubbard model fails to match the spectral features but a straightforward extension to a large attractive nearest-neighbor interaction quantitatively explains our results. Our finding shows the significance of additional interactions beyond the long-predicted quantum spin pairing in the ($d$-wave) charge pairing process. Considering the parallels between ladders and two-dimensional cuprates, these results are potentially relevant for square lattices as well.

cond-mat.str-el↗

arXiv2024

Spectrum and low-temperature bulk properties of triangular quantum spin liquid candidate NaYbSe$_2$

We report neutron scattering, pressure-dependent AC calorimetry, and AC magnetic susceptibility measurements of triangular lattice NaYbSe$_2$. We observe a continuum of scattering, which is reproduced by matrix product simulations, and no phase transition is detected in any bulk measurements. Comparison to heat capacity simulations suggest the material is within the Heisenberg spin liquid phase. AC Susceptibility shows a frequency-dependent peak at 40 mK, as has been observed in several triangular magnets.

cond-mat.str-el↗

arXiv2022

Spin sensitive transport in RuCl_3/Pt heterostructures: revealing a field-transverse spin anisotropy in a spin liquid candidate

Alpha-phase (a-) RuCl_3 has emerged as a possible candidate for a quantum spin liquid (QSL) that promises exotic quasi-particles relevant for fault-tolerant quantum computation. Here, we report spin-sensitive transport measurements using a proximal spin Hall metal -- platinum (Pt) -- to probe magnetic moments in the insulator a-RuCl_3. We observe a spin Hall magnetoresistance (SMR) where both the transverse and longitudinal resistivities of a-RuCl_3/Pt exhibit oscillations as functions of the angle between the in-plane magnetic field and the current, arising from the interplay between the spin Hall effect in Pt and local magnetic moments in a-RuCl3. The oscillations are observed from 1.5 T to 18 T, spanning the range of magnetic fields where zig-zag antiferromagnetic phase, the putative QSL phase, and the partially field-polarized states are reported in a-RuCl_3. The phase of the SMR oscillations suggest that the local moments, regardless of static or fluctuating, in a-RuCl_3 develop an anisotropy with an in-plane quantization axis that aligns largely transverse to the magnetic field for all fields above 1.5 T. Temperature dependance of the SMR revealed that the spin anisotropy has a similar energy scale to reported QSL signatures in a-RuCl_3. The coupling between the spin states within a-RuCl_3 and Pt demonstrated in our experiment opens a transport route to exploring exotic spin phases and device functionalities of QSL materials.

cond-mat.str-el↗