arXiv subjects

Dominic Blosser

Publications and source records attributed to Dominic Blosser.

6 recordsLinked to original sources

arXiv2022

LT-scaling in depleted quantum spin ladders

Using a combination of neutron scattering, calorimetry, Quantum Monte Carlo (QMC) simulations and analytic results we uncover confinement effects in depleted, partially magnetized quantum spin ladders. We show that introducing non-magnetic impurities into magnetized spin ladders leads to the emergence of a new characteristic length L in the otherwise scale-free Tomonaga-Luttinger liquid (serving as the effective low-energy model). This results in universal LT scaling of staggered susceptibilities. Comparison of simulation results with experimental phase diagrams of prototypical spin ladder compounds DIMPY and BPCB yields excellent agreement.

cond-mat.str-el↗

arXiv2020

High pressure Raman study of the quantum magnet (C$_4$H$_{12}$N$_2$)Cu$_2$Cl$_6$

Magnetic and lattice excitations in the quantum antiferromagnet (C$_4$H$_{12}$N$_2$)Cu$_2$Cl$_6$ (PHCC) are studied across two pressure-induced phase transition at $P_c=4.3~\mathrm{kbar}$ and $P_1=13.4~\mathrm{kbar}$ using Raman spectroscopy. It is confirmed that neither transition is a result of a structural transformation. Magnetic scattering is detected. It shows a pronounced pressure dependence and undergoes substantial changes at both transitions. The results are in clear contradiction with previous neutron studies, which detected only minor changes of the magnon spectrum at $P_1$. A number of phonons show anomalous frequency shifts at low temperatures. This effect is pressure dependent and for two of the observed phonons dramatically reverses sign at around $P_1$. The anomalous behavior is attributed to strong magnetoelastic coupling in PHCC.

cond-mat.str-el↗

arXiv2020

Magnetic field induced bound states in spin-$\frac{1}{2}$ ladders

Motivated by the intriguing mode splittings in a magnetic field recently observed with inelastic neutron scattering in the spin ladder compound (C$_5$H$_{12}$N)$_2$CuBr$_4$ (BPCB), we investigate the nature of the spin ladder excitations using DMRG and analytical arguments. Starting from the fully frustrated ladder, for which we derive the low-energy spectrum, we show that bound states are generically present close to $k=0$ in the dynamical structure factor of spin ladders above $H_{c 1}$, and that they are characterized by a field-independent binding energy and an intensity that grows with $H-H_{c 1}$. These predictions are shown to explain quantitatively the split modes observed in BPCB.

cond-mat.str-el↗

arXiv2020

Miniature capacitive Faraday force magnetometer for magnetization measurements at low temperatures and high magnetic fields

A Faraday force magnetometer is presented for measurements of magnetization at temperatures down to 100~mK and in magnetic fields up to 14~T. The specimen is mounted on a flexible cantilever forming a force-sensing capacitor in combination with a fixed back plate. Two different cantilever designs are presented. A torsion resistant cantilever allows to measure magnetization of highly anisotropic single crystal samples. Measurements of the metal organic quantum magnets (C$_5$H$_{12}$N)$_2$CuBr$_4$ (BPCB) and NiCl$_2$$\cdot$4 SC(NH$_2$)$_2$ (DTN) demonstrate the device's capabilities. Routinely, a specimen's magnetic moment is measured with a resolution better than $10^{-7}$ A$\,$m$^2$ ($10^{-4}$ emu). The device in miniaturized to fit is almost any cryostat.

cond-mat.mtrl-sci↗

arXiv2019

Dynamics and field-induced order in the layered spin $S=1/2$ dimer system (C$_5$H$_6$N$_2$F)$_2$CuCl$_4$

The quasi-two-dimensional Heisenberg spin $S=1/2$ dimer system bis(2-amino-5-fluoro-pyridinium) tetrachlorocuprate(II) is studied by means of inelastic neutron scattering, calorimetry and nuclear magnetic resonance (NMR) experiments. In the absence of an applied magnetic field we find dispersive triplet excitations with a spin gap of $Δ=1.112(15)$ meV and a bandwidth of $0.715(15)$ meV within the layers and $0.116(15)$ meV between the layers, respectively. In an applied magnetic field of $μ_0H_c\approx 8.5$ T the spin gap is closed and we find a field induced antiferromagnetically ordered phase.

cond-mat.str-el↗

arXiv2017

Finite-temperature correlations in a quantum spin chain near saturation

Inelastic neutron-scattering and finite-temperature density matrix renormalization group (DMRG) calculations are used to investigate the spin excitation spectrum of the $S=1/2$ Heisenberg spin chain compound K$_2$CuSO$_4$Cl$_2$ at several temperatures in a magnetic field near saturation. Critical correlations characteristic of the predicted $z=2$, $d=1$ quantum phase transition occurring at saturation are shown to be consistent with the observed neutron spectra. The data is well described with a scaling function computed using a free fermion description of the spins, valid close to saturation, and the corresponding scaling limits. One of the most prominent non-universal spectral features of the data is a novel thermally activated longitudinal mode that remains underdamped across most of the Brillouin zone.

cond-mat.str-el↗