Multiferroic Quantum Criticality

Phase transitions are ubiquitous in nature -- water turning to steam is an everyday example. A special kind of phase transition can occur at zero temperature by changing a non-thermal control parameter. Such a quantum phase transition is the driver for exotic quantum critical physics that extends to elevated temperatures [1]. In this talk, I will begin by introducing quantum phase transitions in magnets, which have been widely explored [2]. I will next discuss, the very recently established, ferroelectric quantum critical behavior [3]. Finally, I will present the concept of multiferroic quantum criticality -- in which both magnetic and ferroelectric quantum criticality occur in the same system -- that we have recently proposed [4]. I will describe the associated experimental signatures and material systems to realize it, and highlight possible future directions.

[1] S. Sachdev, Quantum phase transitions (Cambridge University Press, Cambridge, 2011).
[2] P. Gegenwart, Q. Si, and F. Steglich, Nature Physics 4, 186 (2008).
[3] S. Rowley et al., Nature Physics 10, 367 (2014).
[4] A. Narayan, A. Cano, A. V. Balatsky, and N. A. Spaldin, Nature Materials 18, 223 (2019).