Engineering Surface Critical Behavior of (2+1)-Dimensional O(3) Quantum Critical Points

Area of Science:

• Condensed matter physics
• Quantum magnetism
• Surface science

Background:

• Surface critical behavior (SCB) describes singularities at surfaces during bulk phase transitions, offering richer insights than bulk behavior.
• Understanding SCB is crucial for materials science and quantum phenomena at interfaces.
• Previous studies often focused on bulk critical behavior, with surface effects being less explored.

Purpose of the Study:

• To investigate the realization of different SCB universality classes in (2+1)-dimensional O(3) quantum critical points.
• To explore how engineered surface configurations influence SCB.
• To challenge and refine current theoretical understanding of surface phase transitions.

Main Methods:

• Utilizing dimerized Heisenberg models at (2+1)-dimensional O(3) quantum critical points.
• Engineering specific surface configurations to induce different SCB phenomena.
• Analyzing the resulting critical behavior, including surface gap properties and magnetic ordering.

Main Results:

• Demonstrated the occurrence of three distinct SCB universality classes: ordinary, special, and extraordinary transitions.
• Showed that gapped surfaces lead to ordinary transitions, while gapless surfaces result in special transitions.
• Observed an extraordinary transition in the staggered Heisenberg model with ferrimagnetic surface order, exhibiting critical exponents that violate scaling theory.

Conclusions:

• Surface configurations play a critical role in realizing diverse SCB universality classes.
• The findings challenge established scaling theories for extraordinary transitions.
• This work provides new avenues for understanding complex surface phenomena in quantum critical systems.