1 / 20

Electronic Structure and Magnetization of Rare-Earth Nitride Films: Insights from SmN, DyN, and GdN

This study investigates the electronic structures and magnetic properties of rare-earth nitride films, specifically SmN, DyN, and GdN. The unique interplay between localized 4f electrons and delocalized band electrons presents an intriguing theoretical challenge. The experimental methods, including growth under N2, resistivity measurements, and magnetization studies using SQUID, reveal insights into their semiconducting properties and ferromagnetism. Notably, findings include GdN exhibiting ferromagnetism around 68K, alongside evidence of band edge shifts and anomalous resistivity behaviors in SmN and DyN.

elata
Télécharger la présentation

Electronic Structure and Magnetization of Rare-Earth Nitride Films: Insights from SmN, DyN, and GdN

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Rare-earth nitride films Electronic structure of SmN, DyN and GdN

  2. Motivation • Localized 4f electrons and delocalized band electrons - a frontier for theory • Numerous theoretical predictions • Half metals? • No consensus! • Very little experimental data

  3. Experimental investigation of electronic band structure • Methods • Growth (in presence of N2) • Resistivity • Magnetisation (SQUID) • XAS/XES (done at BNL)

  4. Magnetisation… (GdN) • Ferromagnetic, Tc ~ 68K • 7µB/Gd saturation magnetisation Granville et al, “Semiconducting ground state of GdN thin films” Phys. Rev. B, 73, 235335 (2006)

  5. …and Resistivity (GdN) • Shift in the band edge • But still semiconducting! Granville et al, “Semiconducting ground state of GdN thin films” Phys. Rev. B, 73, 235335 (2006)

  6. Resistivity & Magnetisation (DyN) • Semiconducting! • Ferromagnet (28K)

  7. Resistivity & Magnetisation (SmN) • Previously reported as antiferromagnetic • Small moment – relatively large errors • Clear transition ~ 20K

  8. Resistivity & Magnetisation (SmN) • Semiconducting! • Anomaly at transition temperature

  9. X-ray spectroscopy (DyN) • N k-edge, p-projected empty DOS

  10. X-ray spectroscopy (DyN) • Clear evidence of gap between XES and XAS • Must be careful of core hole effects

  11. X-ray spectroscopy (DyN) • Compare directly with band structure calculations (in collaboration with Walter Lambrecht) • Very good agreement!

  12. X-ray spectroscopy (SmN)

  13. X-ray spectroscopy (SmN)

  14. Summary • Semiconductors! • Anomaly in resistivity at Tc – a band shift • X-ray spectroscopy of valence and conduction bands. Theory is getting close! Preston et al, “Band structure of SmN and DyN”, Phys. Rev. Lett., submitted

  15. Acknowledgements • Ben Ruck, Jianping Zhong, Joe Trodahl • Victoria University of Wellington • The MacDiarmid Institute • Walter Lambrecht, Paul Larson • Case Western Reserve University • James Downes • Macquarie University, Sydney • Kevin Smith • Boston University

  16. Extra

  17. Overview • What are they • Rock salt, RE3+ N3- • Stronly localized 4f electrons with band electrons. • Highly reactive (unstable in atmosphere) • and why? • Tough on theory - numerous attempts • No consensus! • No experimental data to guide • Half metals?

  18. Extra Results – XxS (DyN)

  19. Results – XxS (SmN)

  20. Methods • Theoretical • LSDA+U (W.R.L. Lambrecht) • LSD-SIC (Aerts et al) • No consensus!

More Related