# Degenerate soft modes and selective condensation in                    <math>                      <mrow>                        <msub>                          <mi>BaAl</mi>                          <mn>2</mn>                        </msub>                        <msub>                          <mi>O</mi>                          <mn>4</mn>                        </msub>                      </mrow>                    </math>                    via inelastic x-ray scattering

https://mdr.nims.go.jp/datasets/0e21fb9d-3a96-48a3-b2d3-ca5af6f9ffa8

## File

- [2602.01732v1.pdf](https://mdr.nims.go.jp/filesets/2f2ef2f8-1a24-4389-900b-71dfe7265401/download) ([Detail](https://mdr.nims.go.jp/filesets/2f2ef2f8-1a24-4389-900b-71dfe7265401.md))

## Id

0e21fb9d-3a96-48a3-b2d3-ca5af6f9ffa8

## Local identifier



## Visibility

open_to_public

## State

published

## Created at

2026-02-24T01:25:36.748911Z

## Updated at

2026-02-24T01:44:01.061803Z

## Published at

2026-02-24T03:30:20.084496Z

## Doi



## First published url

https://doi.org/10.1103/9nxr-h9zl

## Date published

2026-02-23

## Recorded date published

2026-2

## Resource type

journal_article

## Manuscript type

accepted_manuscript

## Collection



## Title

- title: |-
    Degenerate soft modes and selective condensation in
                        <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
                          <mml:mrow>
                            <mml:msub>
                              <mml:mi>BaAl</mml:mi>
                              <mml:mn>2</mml:mn>
                            </mml:msub>
                            <mml:msub>
                              <mml:mi mathvariant="normal">O</mml:mi>
                              <mml:mn>4</mml:mn>
                            </mml:msub>
                          </mml:mrow>
                        </mml:math>
                        via inelastic x-ray scattering
  title_type: original
  lang: en

## Description

- description: "BaAl2O4 is a ferroelectric material that exhibits structural quantum
    criticality through chemical\r\ncomposition tuning. Although theoretical calculations
    and several diffraction experiments have\r\nsuggested the involvement of a soft
    mode in its ferroelectric structural phase transition, direct\r\nexperimental
    verification is still lacking. In this study, we successfully observed two soft
    modes\r\nof BaAl2O4 using x-ray inelastic scattering, providing direct experimental
    evidence for their role\r\nin the structural phase transition. Furthermore, we
    reveal that the soft modes at the M and K\r\npoints are nearly degenerate in energy,
    indicating a delicate balance in which either mode could\r\npotentially freeze.
    The K-point mode simultaneously softens toward the transition temperature\r\n(TC)
    in a manner nearly identical to the M-point mode. However, the phase transition
    condenses\r\nonly at the M point, with the M-point mode stabilizing as an acoustic
    mode in the low-temperature\r\nstructure and the K-point mode hardening as temperature
    decreases."
  description_type: abstract
  lang: und

## Creator

- name: Yui Ishii
  role: author
  orcid: https://orcid.org/0000-0002-7942-8645
- name: Arisa Yamamoto
  role: author
- name: Alfred Q. R. Baron
  role: author
  orcid: https://orcid.org/0000-0002-5899-2116
- name: Hiroshi Uchiyama
  role: author
  orcid: https://orcid.org/0000-0001-8138-9393
- name: Naoki Sato
  role: author
  orcid: https://orcid.org/0000-0002-6429-0591

## Contact agent



## Publisher

organization: American Physical Society (APS)

## Managing organization



## Keyword

- subject: phonons
  schema: not_defined
- subject: soft modes
  schema: not_defined
- subject: inelastic X-ray scattering
  schema: not_defined

## Rights

- identifier: https://creativecommons.org/licenses/by/4.0/

## Other identifier(s)



## Data origin



## Embargo



## Journal

- title: Physical Review B
  issn: '24699950'
  volume: '113'
  issue: '6'
  article_number: '064112'

## Conference



## Related item



## Funding

- identifier: 23K17673
  funder_name: Japan Society for the Promotion of Science
- identifier: 2020A1179
  funder_name: Japan Synchrotron Radiation Research Institute

## Instrument



## Instrument operator



## Instrument managing organization



## Measurement method



## Specimen



## Chemical composition



## Structure for specimen



## Structural feature for specimen



## Specific property for specimen



## Process for specimen treatment



## Computational method



## Energy level/transition state



## Software



## Custom property



## Fileset

- id: 2f2ef2f8-1a24-4389-900b-71dfe7265401
  filename: 2602.01732v1.pdf
  content_type: application/pdf
  size: 12341815
  md5: 34d7bce09a3fa762fb9d59a35ea7d4a5

## Thumbnail

fileset_id: 2f2ef2f8-1a24-4389-900b-71dfe7265401
filename: 2602.01732v1.pdf