Related papers: Field-induced criticality in a gapped quantum magn…
The strongly correlated system Ho11B12 with boron sublattice Jahn-Teller instability and nanoscale electronic phase separation (dynamic charge stripes) was studied in detail by inelastic neutron scattering (INS), magnetometry and heat…
We report magnetization changes generated by an electric field in ferromagnetic Ga$_{1-x}$Mn$_x$N grown by molecular beam epitaxy. Two classes of phenomena have been revealed. First, over a wide range of magnetic fields, the magnetoelectric…
Rare-earth (RE) kagome-lattice magnets offer an excellent platform to discover the novel magnetic phase as well as quantum phase transition tuned by non-thermal control parameters, while the experimental realizations remain largely…
We report experimental and theoretical studies on the magnetic and thermodynamic properties of NIT-2Py, a free radical-based organic magnet. From magnetization and specific heat measurements we establish the temperature versus magnetic…
We use the Wilson-Fisher $\epsilon$ expansion to study quantum critical behavior in gauged Yukawa matrix field theories with weak quenched disorder. We find that the resulting quantum critical behavior is in the universality class of the…
Critical thermodynamics close to a metamagnetic quantum critical endpoint (QCEP) in a metal is discussed within the framework of spin-fluctuation theory. We analyze the effective potential for the Ising order parameter that is renormalized…
We study the temperature dependence of the conductivity due to quantum interference processes for a two-dimensional disordered itinerant electron system close to a ferromagnetic quantum critical point. Near the quantum critical point, the…
We investigate a zero-temperature itinerant antiferromagnetic transition where the fermions possess a d-wave gap. This problem pertains to both the nodal liquid insulating phase and the d-wave superconducting phase of the underdoped…
We employ unsupervised learning tools to identify different phases and their transition in quantum systems subject to the combined action of unitary evolution and stochastic measurements. Specifically, we consider principal component…
The effect of thermal fluctuations on the dynamics of a gapped quantum magnet is studied using inelastic neutron scattering on copper nitrate, a model material for the one-dimensional (1D) bond alternating Heisenberg chain, combined with…
Using recent insights obtained in heavy fermion physics on the thermodynamic singularity structure associated with quantum phase transitions, we present here an experimental strategy to establish if the zero-temperature transition in the…
Recent experimental and numerical studies of the critical-temperature exponent $\phi$ for the superfluid-Bose glass universality in three-dimensional systems report strong violations of the key quantum critical relation, $\phi=\nu z$, where…
We report the observation of a magnetic-field-induced transition between magnetically disordered and ordered phases in slightly under-doped La(2-x)SrxCuO4 with x=0.144. Static incommensurate spin-density-wave order is induced above a…
Inelastic neutron scattering experiments performed on a single crystal of the antiferromagnetic compound Ce$_{0.87}$La$_{0.13}$Ru$_{2}$Si$_{2}$ under applied pressures of up to 5 kbar are reported. A quantum critical point is reached at…
The intertwining between competing degrees of freedom, anisotropy, and frustration-induced quantum fluctuations offers an ideal ground to realize exotic quantum phenomena in the rare-earth-based kagome lattice. The magnetic susceptibility…
In order to test the recently proposed connection between the neutron resonance and the specific heat anomaly in cuprates, the experimental specific heat data on $YBa_2Cu_3O_{6.93}$ and a theoretical estimate of the single particle…
We calculate the magnetization of a two-dimensional superconductor in a perpendicular magnetic field near its Kosterlitz-Thouless transition and at lower temperatures. We find that the critical behavior is more complex than assumed in the…
Considerable evidence exists for the failure of the traditional theory of quantum critical points (QCPs), pointing to the need to incorporate novel excitations. The destruction of Kondo entanglement and the concomitant critical Kondo effect…
The thesis examines the topics of disorder and electron-electron interactions in three distinct quantum systems. Firstly, the Anderson transition is studied for the BCC and FCC lattices. We obtain high precision results for the critical…
Quantum phase transitions are among the most intriguing phenomena that can occur when the electronic ground state of correlated metals are tuned by external parameters such as pressure, magnetic field or chemical substitution. Such…