# Emergent Ising degrees of freedom above a double-stripe magnetic ground state [Emergent Ising degrees of freedom above double-stripe magnetism]

## Abstract

Here, double-stripe magnetism [Q=(π/2,π/2)] has been proposed as the magnetic ground state for both the iron-telluride and BaTi _{2}Sb _{2}O families of superconductors. Double-stripe order is captured within a J _{1}–J _{2}–J _{3} Heisenberg model in the regime J _{3} >> J _{2} >> J _{1}. Intriguingly, besides breaking spin-rotational symmetry, the ground-state manifold has three additional Ising degrees of freedom associated with bond ordering. Via their coupling to the lattice, they give rise to an orthorhombic distortion and to two nonuniform lattice distortions with wave vector (π,π). Because the ground state is fourfold degenerate, modulo rotations in spin space, only two of these Ising bond order parameters are independent. Here, we introduce an effective field theory to treat all Ising order parameters, as well as magnetic order, and solve it within a large-N limit. All three transitions, corresponding to the condensations of two Ising bond order parameters and one magnetic order parameter are simultaneous and first order in three dimensions, but lower dimensionality, or equivalently weaker interlayer coupling, and weaker magnetoelastic coupling can split the three transitions, and in some cases allows for two separate Ising phase transitions above the magnetic one.

- Authors:

- Ames Lab. and Iowa State Univ., Ames, IA (United States)

- Publication Date:

- Research Org.:
- Ames Laboratory (AMES), Ames, IA (United States)

- Sponsoring Org.:
- USDOE

- OSTI Identifier:
- 1417354

- Alternate Identifier(s):
- OSTI ID: 1414976

- Report Number(s):
- IS-J-9554

Journal ID: ISSN 2469-9950; PRBMDO; TRN: US1801040

- Grant/Contract Number:
- AC02-07CH11358; PHYS-1066293

- Resource Type:
- Journal Article: Accepted Manuscript

- Journal Name:
- Physical Review B

- Additional Journal Information:
- Journal Volume: 96; Journal Issue: 21; 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

### Citation Formats

```
Zhang, Guanghua, and Flint, Rebecca.
```*Emergent Ising degrees of freedom above a double-stripe magnetic ground state [Emergent Ising degrees of freedom above double-stripe magnetism]*. United States: N. p., 2017.
Web. doi:10.1103/PhysRevB.96.214438.

```
Zhang, Guanghua, & Flint, Rebecca.
```*Emergent Ising degrees of freedom above a double-stripe magnetic ground state [Emergent Ising degrees of freedom above double-stripe magnetism]*. United States. doi:10.1103/PhysRevB.96.214438.

```
Zhang, Guanghua, and Flint, Rebecca. Wed .
"Emergent Ising degrees of freedom above a double-stripe magnetic ground state [Emergent Ising degrees of freedom above double-stripe magnetism]". United States.
doi:10.1103/PhysRevB.96.214438.
```

```
@article{osti_1417354,
```

title = {Emergent Ising degrees of freedom above a double-stripe magnetic ground state [Emergent Ising degrees of freedom above double-stripe magnetism]},

author = {Zhang, Guanghua and Flint, Rebecca},

abstractNote = {Here, double-stripe magnetism [Q=(π/2,π/2)] has been proposed as the magnetic ground state for both the iron-telluride and BaTi2Sb2O families of superconductors. Double-stripe order is captured within a J1–J2–J3 Heisenberg model in the regime J3 >> J2 >> J1. Intriguingly, besides breaking spin-rotational symmetry, the ground-state manifold has three additional Ising degrees of freedom associated with bond ordering. Via their coupling to the lattice, they give rise to an orthorhombic distortion and to two nonuniform lattice distortions with wave vector (π,π). Because the ground state is fourfold degenerate, modulo rotations in spin space, only two of these Ising bond order parameters are independent. Here, we introduce an effective field theory to treat all Ising order parameters, as well as magnetic order, and solve it within a large-N limit. All three transitions, corresponding to the condensations of two Ising bond order parameters and one magnetic order parameter are simultaneous and first order in three dimensions, but lower dimensionality, or equivalently weaker interlayer coupling, and weaker magnetoelastic coupling can split the three transitions, and in some cases allows for two separate Ising phase transitions above the magnetic one.},

doi = {10.1103/PhysRevB.96.214438},

journal = {Physical Review B},

number = 21,

volume = 96,

place = {United States},

year = {Wed Dec 27 00:00:00 EST 2017},

month = {Wed Dec 27 00:00:00 EST 2017}

}