Engineering topics

He, Liang

Publications and source records attributed to He, Liang.

3 records

DOE OSTI2023

Observations of xenon spectra on the EAST x-ray crystal spectrometer for high-temperature plasma diagnostics

The Xe 44+ 2.7203 Å line, which has been proposed as one of the diagnostic lines for the x-ray imaging crystal spectrometer on ITER, is observed on the EAST tokamak together with its several satellite lines. The observations are made under high electron temperature (T e ) conditions (core T e > 5 keV). Most of the observed xenon lines are identified by comparing the experiment results with the atomic simulation results. The first ion temperature measurements made by the xenon spectra on EAST are also reported in this article. These xenon spectra observations contribute to the justification for using xenon as the diagnostic impurity in x-ray crystal spectrometers in future reactor-scale high-temperature plasmas.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2022

Crystallizing Kagome Artificial Spin Ice

Artificial spin ices are engineered arrays of dipolarly coupled nanobar magnets. They enable direct investigations of fascinating collective phenomena from their diverse microstates. However, experimental access to ground states in the geometrically frustrated systems has proven difficult, limiting studies and applications of novel properties and functionalities from the low energy states. In this work, we introduce a convenient approach to control the competing diploar interactions between the neighboring nanomagnets, allowing us to tailor the vertex degeneracy of the ground states. We achieve this by tuning the length of selected nanobar magnets in the spin ice lattice. We demonstrate the effectiveness of our method by realizing multiple low energy microstates in a kagome artificial spin ice, particularly the hardly accessible long range ordered ground state—the spin crystal state. Our strategy can be directly applied to other artificial spin systems to achieve exotic phases and explore new emergent collective behaviors.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Self-Intercalation Tunable Interlayer Exchange Coupling in a Synthetic van der Waals Antiferromagnet

One of the most promising avenues in 2D materials research is the synthesis of antiferromagnets employing 2D van der Waals (vdW) magnets. However, it has proven challenging, due in part to the complicated fabrication process and undesired adsorbates as well as the significantly deteriorated ferromagnetism at atomic layers. Here, the engineering of the antiferromagnetic (AFM) interlayer exchange coupling between atomically thin yet ferromagnetic CrTe 2 layers in an ultra-high vacuum-free 2D magnetic crystal, Cr 5 Te 8 is reported. By self-introducing interstitial Cr atoms in the vdW gaps, the emergent AFM ordering and the resultant giant magnetoresistance effect are induced. A large negative magnetoresistance (10%) with a plateau-like feature is revealed, which is consistent with the AFM interlayer coupling between the adjacent CrTe 2 main layers in a temperature window of 30 K below the Néel temperature. Notably, the AFM state has a relatively weak interlayer exchange coupling, allowing a switching between the interlayer AFM and ferromagnetic states at moderate magnetic fields. Here this work represents a new route to engineering low-power devices that underpin the emerging spintronic technologies, and an ideal laboratory to study 2D magnetism.

36 MATERIALS SCIENCE↗