Spatially resolved steady-state negative capacitance

Ajay K. Yadav, Kayla X. Nguyen, Zijian Hong, Pablo García-Fernández, Pablo Aguado-Puente, Christopher T. Nelson, Sujit Das, Bhagawati Prasad, Daewoong Kwon, Suraj Cheema, Asif I. Khan, Chenming Hu, Jorge Íñiguez, Javier Junquera, Long Qing Chen, David A. Muller, Ramamoorthy Ramesh, Sayeef Salahuddin*

*Corresponding author for this work

Research output: Contribution to journalLetter

62 Citations (Scopus)
397 Downloads (Pure)

Abstract

Negative capacitance is a newly discovered state of ferroelectric materials that holds promise for electronics applications by exploiting a region of thermodynamic space that is normally not accessible1–14. Although existing reports of negative capacitance substantiate the importance of this phenomenon, they have focused on its macroscale manifestation. These manifestations demonstrate possible uses of steady-state negative capacitance—for example, enhancing the capacitance of a ferroelectric–dielectric heterostructure4,7,14 or improving the subthreshold swing of a transistor8–12. Yet they constitute only indirect measurements of the local state of negative capacitance in which the ferroelectric resides. Spatial mapping of this phenomenon would help its understanding at a microscopic scale and also help to achieve optimal design of devices with potential technological applications. Here we demonstrate a direct measurement of steady-state negative capacitance in a ferroelectric–dielectric heterostructure. We use electron microscopy complemented by phase-field and first-principles-based (second-principles) simulations in SrTiO3/PbTiO3 superlattices to directly determine, with atomic resolution, the local regions in the ferroelectric material where a state of negative capacitance is stabilized. Simultaneous vector mapping of atomic displacements (related to a complex pattern in the polarization field), in conjunction with reconstruction of the local electric field, identify the negative capacitance regions as those with higher energy density and larger polarizability: the domain walls where the polarization is suppressed.

Original languageEnglish
Pages (from-to)468-471
Number of pages4
JournalNature
Volume565
Issue number7740
Early online date14 Jan 2019
DOIs
Publication statusPublished - 24 Jan 2019

ASJC Scopus subject areas

  • General

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