Nav: Home

Nano-polycrystalline film leads to stronger magnetism compared to single-crystal films

March 17, 2017

To realize the next generation of devices for information processing based on new phenomena such as spintronics, multiferroics, magnetooptics, and magnonics, their constituent materials need to be developed. Recent rapid progress in nanotechnology allows us to fabricate nanostructures that are impossible to obtain in nature.

However, complex magnetic oxides are one of the most complicated material systems in terms of development and analysis. In addition, the detailed mechanism is unknown by which changes in atomic composition that do not affect overall structure lead to drastic changes in material characteristics even though the material structure is similar.

Now, researchers at Spin Electronics Group at Toyohashi Tech and at Myongji University, Harbin Institute of Technology, Massachusetts Institute of Technology, Universidad Técnica Federico Santa María, University of California, San Diego, and Trinity College Dublin found that nanoscale pillar-shaped distribution of iron in strontium titanate (STF) changes its magnetic and magnetooptical response drastically. Surprisingly, the polycrystalline sample showed stronger magnetism than single crystalline film.

"In usual oxide systems, magnetic and magnetooptical effects are stronger in highly ordered structures. In other words, single crystalline material is better for obtaining better magnetic properties," explains Assistant Professor Taichi Goto, "However, iron-substituted strontium titanate deposited at certain oxygen pressure is different."

The STF films were prepared by pulsed laser deposition at various pressures directly on silicon substrate, and crystalline structure and magnetic properties were characterized systematically. A sample deposited at a certain pressure showed significantly stronger magnetism and larger Faraday rotation angle (magnetooptical effects) at room temperature. Several tests analyzing the oxygen stoichiometry and the corresponding Fe valence states, the structure and strain state, and the presence of small-volume fractions of iron revealed that the nanostructure and clustering of the elements enhanced magnetism.

These results show the broad possibility of polycrystalline films being used in silicon-based devices. In this paper, the integration of STF film with 0.1 mm scale optical resonator was demonstrated. Further, the integration of such novel oxides with conventional device concepts would pave a way for interesting systems in the future.
Funding agency:
  • T. G. acknowledges support from the JST PRESTO, JSPS Postdoctoral Fellowships for Research Abroad, Grant-in-Aid for Young Scientists (A) No. 26706009, and Challenging Exploratory Research No. 26600043.
  • C. R. acknowledges support from the NSF DMR1419807 and ECCS1607865 and from FAME, a SRC STARnet Center supported by DARPA and MARCO.
  • H. L. T. acknowledges support from the NSF DMR1419807.
  • P. V. acknowledges support from the Center for Development of Nanoscience and Nanotechnology, CEDENNA, Chile.
  • J. M. F. acknowledges support from Fondecyt Iniciación 11130128 and DGIIP USM, Chile.
  • M.I. acknowledges support from the JSPS Grant-in-Aid for Scientific Research (S) No. 26220902.
This work utilized the shared experimental facilities of the Center for Materials Science and Engineering (CMSE), Award 024006-10 No. NSF DMR1419807.

Reference: Taichi Goto, Dong Hun Kim, Xueyin Sun, Mehmet C. Onbasli, Juan M. Florez, Shyue Ping Ong, Patricio Vargas, Karl Ackland, Plamen Stamenov, Nicolas M. Aimon, Mitsuteru Inoue, Harry L. Tuller, Gerald F. Dionne, J. Michael D. Coey and Caroline A. Ross, "Magnetism and Faraday rotation in oxygen-deficient polycrystalline and single-crystal iron-substituted strontium titanate", Phys. Rev. Applied, 7, 024006 (2017/02/08).

Further information

Toyohashi University of Technology
1-1 Hibarigaoka, Tempaku
Toyohashi, Aichi Prefecture, 441-8580, JAPAN
Inquiries: Committee for Public Relations

Toyohashi University of Technology, which was founded in 1976 as a National University of Japan, is a leading research institute in the fields of mechanical engineering, advanced electronics, information sciences, life sciences, and architecture. Website:

Toyohashi University of Technology

Related Iron Articles:

How nitrogen-fixing bacteria sense iron
New research reveals how nitrogen-fixing bacteria sense iron - an essential but deadly micronutrient.
Getting to the root of how plants tolerate too much iron
Salk scientists have found a major genetic regulator of iron tolerance, a gene called GSNOR.
Stressed plants must have iron under control
When land plants' nutrient availability dwindles, they have to respond to this stress.
Is a great iron fertilization experiment already underway?
Using a new, highly sensitive tracer for human-derived iron falling on the ocean, researchers led by the USF College of Marine Science say we have underestimated the iron we add to the ocean compared to natural sources.
High on iron? It stops anaemia but has a downside
A global study looking at the role that iron plays in 900 diseases has uncovered the impact of both low and high iron levels -- and the news is mixed.
More Iron News and Iron Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...