Nonreciprocal and Non-Hermitian Material Response Inspired by Semiconductor Transistors

Area of Science:

• Condensed Matter Physics
• Electromagnetism
• Materials Science

Background:

• Conventional electromagnetic devices often rely on bulky magnets or complex structures.
• Breaking electromagnetic reciprocity is crucial for applications like isolators and circulators.
• Non-Hermitian and nonreciprocal material properties are key to advanced electromagnetic functionalities.

Purpose of the Study:

• To introduce a novel class of bulk materials exhibiting nonreciprocal and non-Hermitian electromagnetic response.
• To demonstrate a new method for breaking electromagnetic reciprocity using nonlinear materials and electric bias.
• To propose a new design for electromagnetic isolators with potentially superior performance.

Main Methods:

• Theoretical analysis of material nonlinearities under static electric bias.
• Linearization of the permittivity tensor to reveal non-Hermitian and non-transpose symmetric properties.
• Conceptual design of a "MOSFET-metamaterial" isolator.

Main Results:

• Material nonlinearities and electric bias induce a linearized permittivity tensor lacking Hermitian and transpose symmetries.
• The material exhibits tunable energy dissipation or generation based on electric field phase.
• The proposed "MOSFET-metamaterial" isolator shows potential to outperform conventional Faraday isolators due to material gain.

Conclusions:

• A novel paradigm for breaking electromagnetic reciprocity in bulk nonlinear materials using static electric bias has been established.
• Engineered nonreciprocal and non-Hermitian responses offer a new pathway for advanced electromagnetic devices.
• Analogous material responses may be achievable in natural nonequilibrium systems.