Strong-disorder fixed point in the dissipative random transverse-field Ising model

Area of Science:

• Condensed Matter Physics
• Quantum Magnetism
• Statistical Mechanics

Background:

• Understanding quantum systems with disorder and dissipation is crucial for materials science.
• The random transverse Ising model is a key theoretical framework for studying magnetic phase transitions.
• Dissipative effects significantly alter quantum critical phenomena.

Purpose of the Study:

• To investigate the interplay between disorder, quantum fluctuations, and dissipation in a random transverse Ising chain.
• To identify the characteristic length and temperature scales governing the system's behavior.
• To elucidate the influence of frozen clusters on thermodynamic properties and critical scaling.

Main Methods:

• Real-space renormalization group (RNG) technique applied to the random transverse Ising chain.
• Analysis of systems coupled to a dissipative Ohmic bath.
• Identification of a characteristic length scale L* and temperature scale T*.

Main Results:

• A large length scale L* was identified, above which frozen cluster physics dominates.
• Below L*, a strong-disorder fixed point governs scaling near a pseudocritical point.
• In the Griffiths-McCoy region, frozen clusters induce classical low-temperature behavior in susceptibility and specific heat, overriding quantum singularities.

Conclusions:

• Frozen clusters significantly impact the low-temperature thermodynamics of disordered quantum magnets.
• The interplay of disorder and dissipation can lead to classical-like behavior, obscuring quantum critical phenomena.
• The identified scales L* and T* provide crucial benchmarks for understanding these complex quantum systems.