To study these electrons, particularly the important outer electrons, researchers from the RIKEN Advanced Science Institute, Wako, in collaboration with colleagues from the SPring-8 Center, Harima, have advanced an x-ray spectroscopy technique that exploits this wave-like behavior. They then found unique magnetic and electronic properties in experiments on a recently synthesized oxide of iridium, Sr2IrO4.
Normally, the outer electrons of atoms stop orbiting freely around the nucleus, as they are used in the chemical bonds of a material. In the so-called 5d heavier elements such as iridium, however, the motion of an electron and its spin are strongly coupled properties. This coupling allows the electrons to regain some of the freedom of motion lost to the chemical bonds. As a consequence, an unexpected insulating behavior had been predicted for 5d oxides such as Sr2IrO4.
In conventional neutron diffraction spectroscopy, the study of the often complex crystal structure of 5d oxides has been problematic. However, enhancements by the researchers to the resonant x-ray scattering (RXS) technique have enabled them to probe the complete magnetic structure of a compound using this technique alone. “In the past, RXS has only been used to enhance the x-ray signal, whereas we have now opened up a completely new opportunity,” explains Hidenori Takagi who led the research team.
Using interference effects between the different x-ray beams scattered by the crystal, the researchers can obtain the precise details of the electron waves. 5d transition metal oxides such as Sr2IrO4 are particularly amenable to RXS, as their atomic resonances occur at short wavelengths and therefore produce more complete data. In their study of Sr2IrO4, the researchers determined its full magnetic structure and, more importantly, confirmed the full recovery of the electron’s freedom and hence the predicted unique insulating state.
This insulating state interests physicists because, in combination with certain properties of the crystal structure of some 5d oxides, an even more unusual insulting state—a so-called topological insulator—could develop. Topological insulators are rare but important since they could be used in novel electronic applications that exploit the electron’s spin properties. “Experimentally, identifying a topological insulator amongst these compounds, particularly at room temperature, would be the realization of a big dream,” says Takagi. In the search for topological insulators and other unusual magnetic properties of 5d elements, Takagi and colleagues have established RXS as an ideal method of choice.
1. Kim, B. J., Ohsumi, H., Komesu, T., Sakai, S., Morita, T., Takagi, H & Arima, T. Phase-sensitive observation of a spin-orbital Mott state in Sr2IrO4. Science 323, 1329–1332 (2009).
The corresponding author for this highlight is based at the RIKEN Magnetic Materials Laboratory
NASA detects solar flare pulses at Sun and Earth
17.11.2017 | NASA/Goddard Space Flight Center
Pluto's hydrocarbon haze keeps dwarf planet colder than expected
16.11.2017 | University of California - Santa Cruz
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses