Quantum Critical Point in the Itinerant Ferromagnet Ni_{1-x}Rh_{x}

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Critical Phenomena

Background:

• Ferromagnetism in metallic alloys is sensitive to chemical composition.
• Quantum critical points (QCPs) represent phase transitions at absolute zero temperature, driven by quantum fluctuations.

Purpose of the Study:

• To investigate the existence and characteristics of a ferromagnetic quantum critical point in polycrystalline Ni_{1-x}Rh_{x} alloys.
• To understand the electronic and magnetic behavior near the critical concentration.

Main Methods:

• Magnetization measurements to determine magnetic ordering temperature and volume fraction.
• Muon spin relaxation (μSR) spectroscopy to probe magnetic properties.
• Specific heat and thermal expansion measurements to identify non-Fermi liquid behavior.

Main Results:

• A continuous suppression of ferromagnetic ordering temperature to zero at x_{crit}=0.375 was observed.
• Magnetic volume fraction remained 100% up to x_{crit}, indicating a second-order phase transition.
• Non-Fermi liquid behavior, characterized by logarithmic divergences in electronic specific heat and thermal expansion, was found near x_{crit}.

Conclusions:

• The study provides evidence for a chemical substitution-induced ferromagnetic quantum critical point in Ni_{1-x}Rh_{x} alloys.
• The observed non-Fermi liquid behavior is consistent with theoretical predictions for systems tuned to a quantum critical point.