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Published on: March 30, 2017
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Extended stability range of the non-Fermi liquid phase in UCoAl
L Havela1, A V Kolomiets1,2, A V Andreev3
1Department of Condensed Matter Physics, Charles University, Ke Karlovu 5, 12116 Prague 2, Czechia.
Summary
High pressure studies reveal the non-Fermi liquid state in uranium metamagnet UCoAl persists up to 4-5 GPa. Spin fluctuations are crucial but do not show critical behavior at the first-order Ferro-NFL phase transition.
Area of Science:
- Condensed matter physics
- Materials science
- Quantum materials
Background:
- Uranium-based intermetallics like UCoAl exhibit complex magnetic and electronic properties.
- The non-Fermi liquid (NFL) state is a hallmark of strongly correlated electron systems, often linked to quantum criticality.
- Understanding the stability of such states under external stimuli is crucial for materials design.
Purpose of the Study:
- To investigate the stability of the non-Fermi liquid (NFL) state in the uranium-based band metamagnet UCoAl under high hydrostatic pressure.
- To construct the phase diagram of UCoAl by varying pressure and observing changes in magnetic and transport properties.
- To elucidate the role of spin fluctuations in the observed phase transitions.
Main Methods:
- Single crystals of UCoAl (pure and Fe-substituted) were subjected to high-pressure investigations.
- Electrical resistivity and magnetization measurements were performed as a function of pressure.
- Analysis of pressure-dependent data allowed for the construction of a pressure-temperature phase diagram.
Main Results:
- The NFL state in UCoAl was found to persist up to approximately 4-5 GPa.
- Increasing hydrostatic pressure shifts the critical metamagnetic field upwards, while simultaneously reducing the magnetization jump at the transition.
- The transition from the ferromagnetic to the NFL state is of the first order and does not exhibit critical spin fluctuations.
Conclusions:
- High pressure is an effective tool to tune the electronic and magnetic properties of UCoAl, stabilizing the NFL state.
- The observed phase diagram reveals a complex interplay between metamagnetism, ferromagnetism, and the NFL state.
- While spin fluctuations are important, they do not display critical divergence at the Ferro-NFL phase boundary, indicating a first-order transition.
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