Origin of the high Neel temperature in SrTcO3

TL;DR

This paper explains the unusually high Neel temperature in SrTcO3 by analyzing its electronic structure, revealing it is near an itinerant-to-localized transition and challenging traditional localized magnetic models.

Contribution

It introduces a combined band-structure and many-body approach to explain the high Neel temperature in SrTcO3, highlighting its proximity to an itinerant-localized transition.

Findings

SrTcO3 has a Neel temperature four times higher than SrMnO3.

The high Neel temperature is due to SrTcO3 being near the itinerant-localized transition.

Pressure has little effect on SrTcO3's Neel temperature, violating Bloch's rule.

Abstract

We investigate the origin of the high Neel temperature recently found in Tc perovskites. The electronic structure in the magnetic state of SrTcO3 and its 3d analogue SrMnO3 is calculated within a framework combining band-structure and many-body methods. In agreement with experiment, the Neel temperature of SrTcO3 is found to be four times larger than that of SrMnO3. We show that this is because the Tc-compound lies on the verge of the itinerant-to-localized transition, and also has a larger bandwidth, while the Mn-compound lies deeper into the localized side. For SrTcO3 we predict that the Neel temperature depends weakly on applied pressure, in clear violation of Bloch's rule, signaling the complete breakdown of the localized picture.