News / Press Release

National Synchrotron Radiation Research Center Discovers Exciting Material Properties in Heterostructure Featured on Cover of Top International Publication, Creating a Perspective for Next-Gen Electronic Devices
Nanoscale Horizons
The National Synchrotron Radiation Research Center’s (NSRRC) scientist, Der-Hsin Wei, has coordinated an international team consisting of associate professor, Yann-Wen Lan, and postdoctoral researcher, Chun-I Lu from National Taiwan Normal University,  scientist,  and Christian Tusche from Peter Grünberg Institute in Germany, to probe new material properties from existing materials stacked into layered structures. For the past two years, the team conducted a study on “cobalt/molybdenum disulfide (MoS2) heterostructure” using the spectro-microscopy capabilities in “Taiwan Light Source” (TLS) and “Elettra-Sincrotrone Trieste” , Italy. They have concluded that, through the interlayer interaction, the amorphous cobalt film landed on a single layer of molybdenum disulfide can behave as if it is in a crystalline state and thus displays “spontaneous magnetic anisotropy” at room temperature. This finding opens up an all new perspective in designing future spintronic devices. The exceptional finding of their study was published in a top international journal “Nanoscale Horizons” on July 1st, with the distinction of being selected as the inside cover image.

The world is currently facing physical bottlenecks in traditional semiconductor materials. As semiconductor manufacturing processes move towards 3 nm, surpassing the physical extremes of transistors and meeting the expected doubling of transistors every 2 years as dictated by Moore’s Law has become the key technology in development by the semiconductor industry. 2D materials with thickness at the atomic level such as graphene and MoS2 have been hailed as potential candidates for surpassing physical extremes and replacing traditional semiconductor materials such as silicon.

2D materials possess many exceptional properties, such as high conductivity, high strength, adjustable electronic structure, and translucency which is why it has seen huge development potential in the fields of electronics, photonics, sensors, and energy materials. In addition to the physical properties of 2D materials that permit independent applications, combining them with other materials to form “heterostructures” broadens and diversifies the development of 2D materials to create endless possibilities in a world of atomic scales.

This study pioneers the layering of a 1 nm thick of cobalt film on a single layer of molybdenum disulfide to form a cobalt/molybdenum disulfide heterostructure which is then analyzed with “X-ray absorption spectroscopy” (XAS), “photoemission electron microscope” (PEEM), and “X-ray photoemission spectroscopy” (XPS). The study found that the “orbital hybridization” at the interface of heterostructures allowed molybdenum disulfide to induce “spontaneous magnetic anisotropy” in the amorphous cobalt film at room temperature. As such anisotropy is mostly found in crystalline materials, this discovery adds a new possibility in designing future spintronic devices with 2D materials. The exceptional results of this study were published in the top international publication “Nanoscale Horizons” and selected as the cover story.

Magnetic anisotropy refers to magnetic materials’ tendency in retaining the magnetization direction along a certain axis (called the easy axis), this property can be used to define the 0’s and 1’s in digital records. Discovering new materials or artificial structures with engineerable magnetic anisotropy will cast a huge momentum to the advance of modern technology, in particular the spintronics.  Compared to conventional electronics, spintronic devices are known for their lower power consumption which is why they are pursued around the world.

Dr. Der-Hsin Wei stated that this discovery has added another knob, orbital hybridization, to fine-tune the magnetic anisotropy. Future research efforts will delve into the better control of this knob so that new possibilities in the semiconductor and optoelectronics industries can be enabled.