Journal of Physical Chemistry C
Journal of Physical Chemistry C
5 years ago

Evidence of Enhanced Oxygen Vacancy Defects Inducing Ferromagnetism in Multiferroic CaMn7O12 Manganite with Sintering Time

Evidence of Enhanced Oxygen Vacancy Defects Inducing Ferromagnetism in Multiferroic CaMn7O12 Manganite with Sintering Time
Shashikala Jaiswar, K. D. Mandal
We provide the first experimental evidence of oxygen vacancy defect induced ferromagnetism in undoped multiferroic CaMn7O12 (CMO) manganite synthesized from the facile chemical combustion method. The obtained nanocrystalline is characterized by various techniques like TGA, FTIR, XRD, SEM-EDX, AFM, UV-visible, XPS, and SQUID, etc. to confirm the phase purity and crystallinity of CMO. Surface roughness increases with sintering time attributed to the increase of surface oxygen vacancy defects. X-ray photoelectron spectroscopy was carried out to confirm the oxidation state of constituent elements and also provides direct evidence of enhanced oxygen vacancies. UV–vis optical absorption used to infer band gap shift from 1.68 to 1.38 eV, respectively, is also attributed to increases in oxygen vacancy defects. Multiple magnetic phase transition temperatures of 90, 50, and 42 K, respectively, were obtained from the derivative of magnetization. A systematic decrease of full widths at half maxima (fwhm) of dM/dT vs T curves with sintering time indicates strengthening of ferromagnetism (FM). Transition temperature does not change significantly with sintering time, indicating the extrinsic origin of FM. The results of the UV–vis, XPS, and AFM and strengthening of ferromagnetism all are corroborated with each other’s results and also attribute to enhanced oxygen vacancy concentration with sintering time. The origin of FM in undoped CMO manganite with sintering time results from bound magnetic polarons (BMPs) of enhanced iterant and the localized electron of oxygen vacancies trapped center at the surface or interfaces. Our finding also opens a new perspective for exploiting oxygen vacancy defect engineering at surfaces or interfaces in the design of exotic magnetic- and spintronics-based devices.

Publisher URL: http://dx.doi.org/10.1021/acs.jpcc.7b05415

DOI: 10.1021/acs.jpcc.7b05415

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.