Strain-tuned properties of hybrid improper ferroelectric superlattices through first-principles calculations and machine learning

Monirul Shaikh, Madhusudan Karmakar, and Saurabh Ghosh
Phys. Rev. B 101, 054101 – Published 3 February 2020
PDFHTMLExport Citation

Abstract

The hybrid improper ferroelectricity is due to the trilinear coupling between three symmetric phonon modes, and the free energy of the system can be described as Ftri αQ1Q2QP, where α is the coupling constant and Q1 and Q2 are the primary order parameters coupled to the polar mode QP. In the case of Pnma symmetry, the Q1 and Q2 modes are rotation, QRot(a0a0c+), and tilt, QTilt(aac0), of BO6 octahedra, respectively. Here, we perform density functional theory (DFT) calculations along with machine learning (ML) to investigate the effects of biaxial strain on the ferroelectric and magnetic properties for hybrid improper ferroelectric (LaFeO3)1/(LnFeO3)1 superlattices (SLs), where Ln represents Ce, Nd, Sm, Gd, Dy, Y, Tm, and Lu. We have investigated how the polarization, magnetization, and coupling coefficients are modified subject to the external strain. The shift in energy minima in the energy landscape, which is a function of both QRot and QTilt, indicates that the ferroelectric switching can be modulated upon imposing strain. Strain can change the polarization up to 16% with respect to the zero-strain value. In the case of magnetization, we observe a change in the easy axis leading to a change in the magnetic configuration from GxAyFz to FxCyGz upon tensile strain. It is impractical to compute the strain response for all possible (LnFeO3)1/(LnFeO3)1 combinations. To overcome this limitation we perform ML with DFT calculated data within a subset of all the combinations. Using machine learning, we predict the change in polarization upon strain for tolerance τ ranging from 0.844 to 0.902, which covers all the possible (LnFeO3)1/(LnFeO3)1 SL combinations. The prediction by ML is in excellent agreement with the DFT calculations.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
2 More
  • Received 7 September 2019
  • Revised 20 December 2019
  • Accepted 3 January 2020

DOI:https://doi.org/10.1103/PhysRevB.101.054101

©2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Monirul Shaikh1, Madhusudan Karmakar1, and Saurabh Ghosh1,2,*

  • 1Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankulathur 603 203, Tamil Nadu, India
  • 2SRM Research Institute, SRM Institute of Science and Technology, Kattankulathur 603 203, Tamil Nadu, India

  • *saurabhghosh2802@gmail.com

Article Text (Subscription Required)

Click to Expand

Supplemental Material (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 101, Iss. 5 — 1 February 2020

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×