With the advent of topology in electronic materials the number of predicted quantum phases has li... more With the advent of topology in electronic materials the number of predicted quantum phases has literally exploded. Most of them, however, still await firm experimental identification. In strongly correlated electron systems, scanning their low-temperature phase diagrams by varying a nonthermal control parameter has been instrumental in delineating phases defined by a Landau order parameter. Here we show that this approach is versatile also for strongly correlated topological phases. We use Hall effect measurements to probe how the time reversal symmetry invariant Weyl-Kondo semimetal Ce$_3$Bi$_4$Pd$_3$ transforms under magnetic-field tuning. We detect an intriguing two-stage transition, which we associate with an annihilation of the Weyl nodes, making the system more insulating, and a consecutive transition to a heavy fermion metal phase. We expect our work to stimulate tuning studies in related systems, thereby advancing the much needed identification of organizing principles for s...
Thermodynamic and inelastic neutron scattering data evidence dynamical scaling in quantum critica... more Thermodynamic and inelastic neutron scattering data evidence dynamical scaling in quantum critical candidate Weyl-Kondo semimetal.
We report 105Pd nuclear magnetic resonance (NMR) and nuclear quadrupolar resonance (NQR) measurem... more We report 105Pd nuclear magnetic resonance (NMR) and nuclear quadrupolar resonance (NQR) measurements on a single crystal of Ce3Pd20Si6, where antiferroquadrupolar and antiferromagnetic orders develop at low temperature. From the analysis of NQR and NMR spectra, we have determined the electric field gradient (EFG) tensors and the anisotropic Knight shift (K) components for both inequivalent Pd sites—Pd(32f) and Pd(48h). The observed EFG values are in excellent agreement with our state-of-the-art density functional theory calculations. The principal values of the quadrupolar coupling are MHz and MHz, for the Pd(32f) and Pd(48h) sites, respectively, which is large compared to the Larmor frequency defined by the gyromagnetic constant MHz/T for 105Pd. Therefore, the complete knowledge of K and the EFG tensors is crucial to establish the correspondence between NMR spectra and crystallographic sites, which is needed for a complete analysis of the magnetic structure, static spin susceptibi...
Vacancy filling by Ga substitution enhances the TE performance of type-I clathrates via improving... more Vacancy filling by Ga substitution enhances the TE performance of type-I clathrates via improving charge carrier mobility.
Proceedings of the National Academy of Sciences, 2011
The presence of a quantum-critical point (QCP) can significantly affect the thermodynamic propert... more The presence of a quantum-critical point (QCP) can significantly affect the thermodynamic properties of a material at finite temperatures T . This is reflected, e.g., in the entropy landscape S ( T , r ) in the vicinity of a QCP, yielding particularly strong variations for varying the tuning parameter r such as pressure or magnetic field B . Here we report on the determination of the critical enhancement of ∂ S /∂ B near a B -induced QCP via absolute measurements of the magnetocaloric effect (MCE), (∂ T /∂ B ) S and demonstrate that the accumulation of entropy around the QCP can be used for efficient low-temperature magnetic cooling. Our proof of principle is based on measurements and theoretical calculations of the MCE and the cooling performance for a Cu 2+ -containing coordination polymer, which is a very good realization of a spin-½ antiferromagnetic Heisenberg chain—one of the simplest quantum-critical systems.
With the advent of topology in electronic materials the number of predicted quantum phases has li... more With the advent of topology in electronic materials the number of predicted quantum phases has literally exploded. Most of them, however, still await firm experimental identification. In strongly correlated electron systems, scanning their low-temperature phase diagrams by varying a nonthermal control parameter has been instrumental in delineating phases defined by a Landau order parameter. Here we show that this approach is versatile also for strongly correlated topological phases. We use Hall effect measurements to probe how the time reversal symmetry invariant Weyl-Kondo semimetal Ce$_3$Bi$_4$Pd$_3$ transforms under magnetic-field tuning. We detect an intriguing two-stage transition, which we associate with an annihilation of the Weyl nodes, making the system more insulating, and a consecutive transition to a heavy fermion metal phase. We expect our work to stimulate tuning studies in related systems, thereby advancing the much needed identification of organizing principles for s...
Thermodynamic and inelastic neutron scattering data evidence dynamical scaling in quantum critica... more Thermodynamic and inelastic neutron scattering data evidence dynamical scaling in quantum critical candidate Weyl-Kondo semimetal.
We report 105Pd nuclear magnetic resonance (NMR) and nuclear quadrupolar resonance (NQR) measurem... more We report 105Pd nuclear magnetic resonance (NMR) and nuclear quadrupolar resonance (NQR) measurements on a single crystal of Ce3Pd20Si6, where antiferroquadrupolar and antiferromagnetic orders develop at low temperature. From the analysis of NQR and NMR spectra, we have determined the electric field gradient (EFG) tensors and the anisotropic Knight shift (K) components for both inequivalent Pd sites—Pd(32f) and Pd(48h). The observed EFG values are in excellent agreement with our state-of-the-art density functional theory calculations. The principal values of the quadrupolar coupling are MHz and MHz, for the Pd(32f) and Pd(48h) sites, respectively, which is large compared to the Larmor frequency defined by the gyromagnetic constant MHz/T for 105Pd. Therefore, the complete knowledge of K and the EFG tensors is crucial to establish the correspondence between NMR spectra and crystallographic sites, which is needed for a complete analysis of the magnetic structure, static spin susceptibi...
Vacancy filling by Ga substitution enhances the TE performance of type-I clathrates via improving... more Vacancy filling by Ga substitution enhances the TE performance of type-I clathrates via improving charge carrier mobility.
Proceedings of the National Academy of Sciences, 2011
The presence of a quantum-critical point (QCP) can significantly affect the thermodynamic propert... more The presence of a quantum-critical point (QCP) can significantly affect the thermodynamic properties of a material at finite temperatures T . This is reflected, e.g., in the entropy landscape S ( T , r ) in the vicinity of a QCP, yielding particularly strong variations for varying the tuning parameter r such as pressure or magnetic field B . Here we report on the determination of the critical enhancement of ∂ S /∂ B near a B -induced QCP via absolute measurements of the magnetocaloric effect (MCE), (∂ T /∂ B ) S and demonstrate that the accumulation of entropy around the QCP can be used for efficient low-temperature magnetic cooling. Our proof of principle is based on measurements and theoretical calculations of the MCE and the cooling performance for a Cu 2+ -containing coordination polymer, which is a very good realization of a spin-½ antiferromagnetic Heisenberg chain—one of the simplest quantum-critical systems.
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Papers by Andrey Prokofiev