Related Experiment Video
Updated: May 1, 2026

Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser
Published on: June 28, 2018
Topological order in an entangled SU(2) ⊗ XY spin-orbital ring
Wojciech Brzezicki1, Jacek Dziarmaga1, Andrzej M Oleś2
1Marian Smoluchowski Institute of Physics, Jagellonian University, Reymonta 4, PL-30059 Kraków, Poland.
Closing a one-dimensional spin-orbital model chain reveals novel topological order. Spins become interdependent on the ring topology, unlike in open chains, leading to unique ground state properties and excitations.
Area of Science:
- Condensed Matter Physics
- Quantum Materials
- Topological Phases of Matter
Background:
- One-dimensional spin-orbital models with SU(2) spin and XY orbital interactions typically separate spin and orbital degrees of freedom on open chains.
- The concept of topological order describes exotic phases of matter characterized by robust ground state degeneracies and fractionalized excitations.
- Ring topology in condensed matter systems can lead to unique phenomena not observed in linear or open chain configurations.
Purpose of the Study:
- To investigate the emergence of topological order in a one-dimensional spin-orbital model when transitioning from an open to a ring (periodic) topology.
- To analyze the interdependence of spin and orbital degrees of freedom under different topological constraints.
- To characterize the ground state properties and low-energy excitations of the model on a closed ring.
Main Methods:
- Utilized a unitary transformation to analyze the spin and orbital interactions.
- Investigated the model's behavior on both open and closed (ring) chain topologies.
- Examined ground state degeneracy and excitation spectra as a function of total quasimomentum.
Main Results:
- On a closed ring, spins become interdependent and form two half-rings with opposite quasimomenta, unlike their separation on an open chain.
- Transitioning from open to periodic topology partially lifts the ground state degeneracy.
- Low-energy excitations exhibit a novel quadratic dispersion relation with respect to the total quasimomentum.
Conclusions:
- The ring topology induces a novel type of topological order in the spin-orbital model, breaking the independent behavior of spins and orbitals.
- This emergent topological order, characterized by specific ground state and excitation properties, is reminiscent of the behavior seen in the infinite-U Hubbard chain.
- Topology plays a crucial role in dictating the quantum phases and emergent phenomena in one-dimensional interacting systems.
Related Concept Videos
The Pauli Exclusion Principle
Atomic Nuclei: Nuclear Spin State Overview
Valence Bond Theory
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
Molecular Orbital Theory II
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...

