Title: Magnetic phase transitions in quantum spin-orbital liquids

Abstract

Here, we investigate the spin and orbital correlations of a superexchange model with spin $$\textit{S}$$ = 1 and orbital $$\textit{L}$$ = 1 relevant for $5d^4$ transition-metal Mott insulators, using exact diagonalization and density matrix renormalization group (DMRG). For spin-orbit coupling λ = 0, the orbitals are in an entangled state that is decoupled from the spins. We find two phases with increasing λ: (I) the $$\textit{S}$$2 phase with two peaks in the structure factor for λ ≤ λ$$_{c1}$$ ≈ 0.34$$\textit{J}$$ where $$\textit{J}$$ is the ferromagnetic exchange; and, (II) the $$\textit{S}$$1 phase for λ$$_{c1}$$ < λ ≤ λ$$_{c2}$$ ≈ 1.2$$\textit{J}$$ with emergent antiferromagnetic correlations. Both $$\textit{S}$$1 and $$\textit{S}$$2 phases are shown to exhibit power-law correlations, indicative of a gapless spectrum. Upon increasing λ > λ$$_{c2}$$ leads to a product state of local spin-orbital singlets that exhibit exponential decay of correlations, indicative of a gapped phase. We obtain insights into the phases from the well-known Uimin-Lai-Sutherland model in an external field that provides an approximate description of our model within mean-field theory.

Authors:

Feng, Shi  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-0184-7049"

Patel, Niravkumar D. ^[1]; Kim, Panjin  ^[2];

• Search DOE PAGES for author "Kim, Panjin"
• Search DOE PAGES for ORCID "0000-0002-2657-311X"

Han, Jung Hoon  ^[3];

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• Search DOE PAGES for ORCID "0000-0002-8026-3833"

Trivedi, Nandini ^[1]

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+ Show Author Affiliations

1. The Ohio State Univ., Columbus, OH (United States)
2. National Security Research Institute, Daejeon (Korea)
3. Sungkyunkwan University, Suwon (Korea)

Publication Date:

Fri Apr 10 00:00:00 EDT 2020

Research Org.:

The Ohio State Univ., Columbus, OH (United States)

Sponsoring Org.:

USDOE Office of Science (SC); Samsung Science and Technology Foundation

OSTI Identifier:

1800477

Grant/Contract Number:  

FG02-07ER46423

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review B

Additional Journal Information:

Journal Volume: 101; Journal Issue: 15; Journal ID: ISSN 2469-9950

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Materials Science; Physics