Quantum Protectorate and Microscopic Models of Magnetism

TL;DR

This paper explores the concept of quantum protectorate in the context of quantum magnetism, proposing that quasi-particle spectra can guide the selection of microscopic models for magnetic materials.

Contribution

It introduces the application of the quantum protectorate concept to quantum magnetism, linking microscopic model selection to quasi-particle excitation spectra.

Findings

Quantum protectorate helps understand model formulation difficulties.

Dual electron behavior is key to modeling magnetic properties.

Quasi-particle spectra serve as criteria for model relevance.

Abstract

Some physical implications involved in a new concept, termed the "quantum protectorate" (QP), are developed and discussed. This is done by considering the idea of quantum protectorate in the context of quantum theory of magnetism. It is suggested that the difficulties in the formulation of quantum theory of magnetism at the microscopic level, that are related to the choice of relevant models, can be understood better in the light of the QP concept . We argue that the difficulties in the formulation of adequate microscopic models of electron and magnetic properties of materials are intimately related to dual, itinerant and localized behaviour of electrons. We formulate a criterion of what basic picture describes best this dual behaviour. The main suggestion is that quasi-particle excitation spectra might provide distinctive signatures and good criteria for the appropriate choice of the relevant model.