Nuclear spin driven quantum relaxation in LiY0.998Ho0.002F4

Area of Science:

• Condensed Matter Physics
• Quantum Magnetism
• Materials Science

Background:

• Investigating quantum phenomena in magnetic materials at cryogenic temperatures is crucial for understanding fundamental physics.
• Holmium-doped LiYF4 (Lithium Yttrium Fluoride) exhibits complex magnetic behaviors due to its electronic structure and hyperfine interactions.

Purpose of the Study:

• To investigate the origin of staircaselike hysteresis loops observed in LiY0.998Ho0.002F4 single crystals.
• To explore the role of quantum dynamics, hyperfine interactions, and spin relaxation mechanisms in the observed magnetic behavior.

Main Methods:

• Magnetic hysteresis measurements were performed on a LiY0.998Ho0.002F4 single crystal at subkelvin temperatures.
• Variable field sweep rates were employed to distinguish between equilibrium and non-equilibrium magnetic transitions.
• Theoretical analysis focused on quantum dynamics at avoided level crossings and the influence of hyperfine interactions.

Main Results:

• Staircaselike hysteresis loops were observed at low temperatures and low magnetic field sweep rates.
• This behavior is attributed to quantum tunneling and relaxation dynamics at avoided energy level crossings of Ho3+ ions.
• Magnetization oscillations and additional steps were observed at faster sweep rates, indicating non-equilibrium spin dynamics.

Conclusions:

• The study demonstrates that quantum dynamics, specifically tunnel splittings and enhanced quantum relaxation, govern the low-temperature magnetic properties of LiY0.998Ho0.002F4.
• Spin-phonon and spin-spin interactions play a significant role in non-equilibrium magnetic transitions at higher sweep rates.
• This research provides a deeper understanding of quantum effects in dilute magnetic systems.