A Gallery of Soft Modes: Theory and Experiment at a Ferromagnetic Quantum Phase Transition
arXiv:2408.03510 · doi:10.1103/PhysRevB.110.134420
Abstract
We examine the low-energy excitations in the vicinity of the quantum critical point in LiHoF, a physical realization of the Transverse Field Ising Model, focusing on the long-range fluctuations which soften to zero energy at the ferromagnetic quantum phase transition. Microwave spectroscopy in tunable loop-gap resonator structures identifies and characterizes the soft mode and higher-energy electronuclear states. We study these modes as a function of frequency and magnetic fields applied transverse and parallel to the Ising axis. These are understood in the context of a theoretical model of a soft electronuclear mode that interacts with soft photons as well as soft phonons. We identify competing infrared divergences at the quantum critical point, coming from the photons and the electronuclear soft mode. It is an incomplete cancellation of these divergences that leads to the muted but distinct signatures observed in the experiments. The application of a longitudinal magnetic field gaps the soft mode. Measurements well away from the quantum critical point reveal a set of ``Walker'' modes associated with ferromagnetic domain dynamics.
20 pages, 14 figures
References in corpus (38)
- Cavity Optomechanics
- Adiabatic Quantum Computing
- High cooperativity in coupled microwave resonator ferrimagnetic insulator hybrids
- Theory of the spin bath
- Cavity Magnonics
- Efficient and robust analysis of complex scattering data under noise in microwave resonators
- Low-Temperature Quantum Relaxation in a System of Magnetic Nanomolecules
- Hybrid magnonics: physics, circuits and applications for coherent information processing
- Influence of Generic Scale Invariance on Classical and Quantum Phase Transitions
- Decoherence in Crystals of Quantum Molecular Magnets
- Low's Subleading Soft Theorem as a Symmetry of QED
- Supercurrent in a room temperature Bose-Einstein magnon condensate
- Infrared Divergences in QED, Revisited
- Rare-Earth Molecular Crystals with Ultra-narrow Optical Linewidths for Photonic Quantum Technologies
- Quantum Phase Transition of a Magnet in a Spin Bath
- On-chip coherent microwave-to-optical transduction mediated by ytterbium in YVO
- Subleading soft photons and large gauge transformations
- Theory of the Magnetic phase diagram of LiHoF
- BMS Supertranslation Symmetry Implies Faddeev-Kulish Amplitudes
- Local Defect in Metallic Quantum Critical Systems
- Study of the cavity-magnon-polariton transmission line shape
- Microwave to optical photon conversion via fully concentrated rare-earth ion crystals
- Dipolar interaction and incoherent quantum tunneling: a Monte Carlo study of magnetic relaxation
- Broadband loop gap resonator for nitrogen vacancy centers in diamond
- Cross-relaxation and phonon bottleneck effects on magnetization dynamics in LiYF4:Ho3+
- Subleading soft dressings of asymptotic states in QED and perturbative quantum gravity
- Perturbative Quantum Monte Carlo Study of LiHoF4 in a Transverse Magnetic Field
- Adiabatic Quantum Search in Open Systems
- 3D Lumped LC Resonators as Low Mass Axion Haloscopes
- Singular Effects of Impurities near the Ferromagnetic Quantum-Critical Point
- 'Hole-digging' in ensembles of tunneling Molecular Magnets
- Loop-gap Microwave Resonator for Hybrid Quantum Systems
- The ferromagnetic transition and domain structure in LiHoF4
- LiHoF: Cuboidal Demagnetizing Factor in an Ising Ferromagnet
- A functional approach to soft graviton scattering and BMS charges
- Theory of magnon-polaritons in quantum Ising materials
- Adjustable coupling and in-situ variable frequency EPR probe with loop-gap resonators for spectroscopy up to X-band
- Soft Theorems from Boundary Terms in the Classical Point Particle Currents