Unique and unusual properties of layered ferrielectric CuInP<sub>2</sub>S<sub>6 </sub>– II. Experimental

ORAL

Abstract

The multifunctionality and van der Waals (vdW) layered structure of CuInP2S6 provides opportunities to achieve ultrathin electromechanical devices. The orientation and magnitude of the polarization in CuInP2S6 is determined by the position of Cu ions, which following theoretical predictions of 4 polarization states can either reside within layers or displace into the vdW gap (theoretical abstract by L. Tao).1 These four stable uniaxial polarization states can be identified using a combination of density functional theory and scanning probe microscopy. Cu is also the most mobile ion, which leads to a unique interplay of ionic and ferroelectric properties that allows polarization alignment against an electric field.2 This type of switching is underpinned by Cu motion across the vdW gap activated by the electric field. Based on this phenomenon, a polarization switching regime associated with negative capacitance is accessible.3 Similar functionality is expected in other materials where polar and ionic properties manifest in the same ionic sublattice.
1Brehm et al, Nat Mater 19:43, 2020
2Neumayer et al, Phys Rev Appl 13:064063, 2020
3Neumayer et al, Adv Energy Mater 10:2001726, 2020

*Supported by US DOE, Office of Science, BES, MSTD and CNMS which is a DOE Office of Science User Facility.

–

Presenters

  • Sabine Neumayer

    • Oak Ridge National Laboratory
    • Oak Ridge National Lab

Authors

  • Sabine Neumayer

    • Oak Ridge National Laboratory
    • Oak Ridge National Lab

  • Lei Tao

    • Vanderbilt University

  • John Brehm

    • Drexel University

  • Andrew O'Hara

    • Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA
    • Department of Physics and Astronomy, Vanderbilt University
    • Department of Physics and Astronomy, Vanderbilt University, Nashville, TN
    • Vanderbilt University

  • Mengwei Si

    • Purdue University

  • Pai-Ying Liao

    • Purdue University

  • Peide (Peter) Ye

    • Purdue University

  • Michael A McGuire

    • Materials Science and Technology Division, Oak Ridge National Laboratory
    • Oak Ridge National Lab
    • Oak Ridge National Laboratory

  • Michael Susner

    • Air Force Research Laboratory
    • Air Force Research Lab - WPAFB

  • Sokrates T Pantelides

    • Department of Physics and Engineering, Vanderbilt University
    • Department of Physics and Astronomy, Vanderbilt Univ
    • Department of Physics and Astronomy, Vanderbilt University
    • Vanderbilt Univ
    • Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA
    • Institute of Physics, Chinese Academy of Sciences
    • Department of Physics and Astronomy & Department of Electrical Engineering and Computer Science, Vanderbilt University
    • Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN
    • Department of Electrical Engineering and Computer Science, Vanderbilt University
    • Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science, Vanderbilt University
    • Vanderbilt University

  • Petro Maksymovych

    • Oak Ridge National Laboratory
    • Oak Ridge National Lab

  • Nina Balke

    • Oak Ridge National Laboratory
    • Oak Ridge National Lab