Tehničko veleučilište u Zagrebu · Zagreb

The Frustration of being Odd: How Boundary Conditions can destroy Local Order

izvorni znanstveni rad

izvorni znanstveni rad

The Frustration of being Odd: How Boundary Conditions can destroy Local Order

Vrsta prilog u časopisu
Tip izvorni znanstveni rad
Godina 2019
Časopis New journal of physics
Nadređena publikacija New journal of physics
Volumen 22
Stranice 083024, 9
DOI 10.1088/1367-2630/aba064
ISSN 1367-2630
Status objavljeno

Sažetak

A central tenant in the classification of phases is that boundary conditions cannot affect the bulk properties of a system. In this work, we show striking, yet puzzling, evidence of a clear violation of this assumption. We use the prototypical example of an XYZ chain with no external field in a ring geometry with an odd number of sites and both ferromagnetic and antiferromagnetic interactions. In such a setting, even at finite sizes, we are able to calculate directly the spontaneous magnetizations that are traditionally used as order parameters to characterize the system's phases. When ferromagnetic interactions dominate, we recover magnetizations that in the thermodynamic limit lose any knowledge about the boundary conditions and are in complete agreement with standard expectations. On the contrary, when the system is governed by antiferromagnetic interactions, the magnetizations decay algebraically to zero with the system size and are not staggered, despite the AFM coupling. We term this behavior ferromagnetic mesoscopic magnetization. Hence, in the antiferromagnetic regime, our results show an unexpected dependence of a local, one-- spin expectation values on the boundary conditions, which is in contrast with predictions from the general theory.

Ključne riječi

Order Parameter ; Frustration ; boundary conditions ; spin chain