Field-Induced Modulated State in the Ferromagnet PrPtAl

Area of Science:

• Condensed matter physics
• Quantum magnetism

Background:

• Quantum order-by-disorder (QOBD) theory describes modulated magnetic states at the transition between ferromagnetic and paramagnetic phases.
• PrPtAl has been proposed as a model system for QOBD phenomena.

Purpose of the Study:

• To investigate the magnetic phase diagram of PrPtAl under applied magnetic fields along both easy (a-axis) and hard (b-axis) directions.
• To test the applicability of QOBD theory in explaining field-induced modulated magnetic states.

Main Methods:

• Magnetic field application along a and b axes.
• Resistivity measurements to analyze the T^2 coefficient.
• Inelastic neutron scattering to detect magnetic fluctuations.

Main Results:

• Magnetic transition temperatures are suppressed by fields applied along the b-axis.
• A single modulated fan state emerges at low temperatures, separating ferromagnetic and field-polarized states.
• Significant increases in the T^2 resistivity coefficient and enhanced magnetic fluctuations were observed in the fan state region.

Conclusions:

• The observed fan state in PrPtAl under magnetic field is well-explained by QOBD theory, incorporating anisotropy and external field effects.
• Experimental evidence confirms the role of QOBD in generating field-induced modulated magnetic states that persist to low temperatures.