Emergent Moments and Random Singlet Physics in a Majorana Spin Liquid

Area of Science:

• Condensed Matter Physics
• Quantum Magnetism
• Disordered Systems

Background:

• Understanding exotic quantum phases like spin liquids is crucial for novel electronic properties.
• The role of quenched disorder in modifying quantum phases remains a key research area.
• Emergent phenomena in strongly correlated electron systems are of significant theoretical interest.

Purpose of the Study:

• To investigate an exactly solvable model of a SU(2) symmetric Majorana spin liquid phase.
• To analyze the impact of quenched disorder (vacancy and bond) on emergent magnetic moments.
• To characterize the low-temperature magnetic susceptibility and its underlying phenomenology.

Main Methods:

• Development of an exactly solvable S=1/2 model on a decorated honeycomb lattice.
• Analysis of site-diluted and bond-disordered systems.
• Theoretical investigation of low-temperature magnetic susceptibility, χ(T).

Main Results:

• Identification of a strong-disorder fixed point governing low-temperature susceptibility.
• Observed susceptibility follows χ(T)=C/T+DT^{α(T)-1}, with α(T)→0 as T→0.
• Distinction between vacancy-induced Curie tail (spin textures) and random singlet phase contributions.

Conclusions:

• The study provides an exactly solvable example of disorder-driven random-singlet phenomenology in a Majorana spin liquid.
• Vacancy disorder creates intrinsic spin textures, contributing a Curie tail to susceptibility.
• Both vacancy and bond disorder lead to a random singlet phase, impacting low-temperature magnetic properties.