Publications by Alexander Kvasov

Structure and pressure-induced ferroelectric phase transition in antiphase domain boundaries of strontium titanate from first principles

Nava Setter, Alexander Tagantsev, Alexander Kvasov

In this work, using zero kelvin ab initio calculations, we revisit the structure and ferroelectric phase transition in antiphase domain boundaries (APBs) in SrTiO3 (STO), which has been previously addressed in terms of a phenomenological approach. We confi ...

Amer Physical Soc2016

Piezoelectric enhancement under negative pressure

Nava Setter, Alexander Tagantsev, Silviu Cosmin Sandu, Jin Wang, Tomas Sluka, Alexander Kvasov

Enhancement of ferroelectric properties, both spontaneous polarization and Curie temperature under negative pressure had been predicted in the past from first principles and recently confirmed experimentally. In contrast, piezoelectric properties are expec ...

Nature Publishing Group2016

A dynamic operation of a PIN photodiode

Maher Kayal, Serguei Okhonin, Alexander Tagantsev, Marc Pastre, Adil Koukab, Denis Sallin, Maxim Gureev, Alexander Kvasov

Traditionally, photodiodes operate at static reverse bias, and incident light intensity is obtained from the relatively week photocurrent. In this paper, we introduce a different concept of photodiode function: the photodiode is used in a dynamic regime wh ...

American Institute of Physics2015

Dynamic flexoelectric effect in perovskites from first-principles calculations

Alexander Tagantsev, Alexander Kvasov

Using the dynamical matrix of a crystal obtained from ab initio calculations, we have evaluated the strength of the dynamic flexoelectric effect and found it comparable to that of the static bulk flexoelectric effect, in agreement with earlier order-of-mag ...

Amer Physical Soc2015

Negative-pressure-induced enhancement in a freestanding ferroelectric

Nava Setter, Alexander Tagantsev, Marco Cantoni, Brahim Dkhil, Silviu Cosmin Sandu, Jin Wang, Tomas Sluka, Alexander Kvasov, Xiankui Wei

Ferroelectrics are widespread in technology(1), being used in electronics and communications(2), medical diagnostics and industrial automation. However, extension of their operational temperature range and useful properties is desired(3-5). Recent developm ...

Nature Publishing Group2015

Ferroelectric translational antiphase boundaries in nonpolar materials

Nava Setter, Alexander Tagantsev, Alexander Kvasov, Xiankui Wei

Ferroelectric materials are heavily used in electro-mechanics and electronics. Inside the ferroelectric, domain walls separate regions in which the spontaneous polarization is differently oriented. Properties of ferroelectric domain walls can differ from t ...

Nature Research2014

High-order electromechanical couplings in ferroelectrics

Alexander Kvasov

EPFL2014

Thin film bulk acoustic wave resonators tuning from first principles

Alexander Tagantsev, Alexander Kvasov

Being important for the antiresonance frequency tuning of tunable thin Film Bulk Acoustic wave Resonators (FBARs), the non-linear electrostrictive coefficient was for the first time calculated for BaTiO3 and SrTiO3 using ab initio methods. Further, taking ...

American Institute of Physics2013

Role of high-order electromechanical coupling terms in thermodynamics of ferroelectric thin films

Alexander Tagantsev, Alexander Kvasov

Currently used methods for the description of thermodynamics of ferroelectric thin films (Landau theory or ab initio based Monte Carlo simulations) are based on an energy expansion in terms of internal degrees of freedom. It was shown that these methods ca ...

American Physical Society2013

Positive effective Q(12) electrostrictive coefficient in perovskites

Alexander Tagantsev, Alexander Kvasov

It is demonstrated that for classical perovskites, such as BaTiO3; SrTiO3, and PbTiO3, electrostrictive strain induced by an electric field may not obey traditionally considered "extension along the field and contraction perpendicular to it" behavior if th ...

American Institute of Physics2012