Topological materials as promising candidates for tuneable helicity-dependent terahertz emitters

Proceedings of SPIE SPIE, the international society for optics and photonics 12683 (2023) 1268302-1268302-2-1268302-1268302-2

Authors:

Jessica L Boland, Djamshid A Damry, Chelsea Q Xia, Yahya Saboon, Abdul Mannan, Piet Schönherr, Dharmalingam Prabhakaran, Laura M Herz, Thorsten Hesjedal, Michael B Johnston

Wafer-Scale Epitaxial Growth of the Thickness-Controllable Van Der Waals Ferromagnet CrTe2 for Reliable Magnetic Memory Applications

Advanced Functional Materials (2023)

Authors:

X Liu, P Huang, Y Xia, L Gao, L Liao, B Cui, D Backes, G van der Laan, T Hesjedal, Y Ji, P Chen, Y Zhang, F Wu, M Wang, J Zhang, G Yu, C Song, Y Chen, Z Liu, Y Yang, Y Peng, G Li, Q Yao, X Kou

Abstract:

To harness the intriguing properties of 2D van der Waals (vdW) ferromagnets (FMs) for versatile applications, the key challenge lies in the reliable material synthesis for scalable device production. Here, the epitaxial growth of single-crystalline 1T-CrTe2 thin films on 2-inch sapphire substrates are demonstrated. Benefiting from the uniform surface energy of the dangling bond-free Al2O3(0001) surface, the layer-by-layer vdW growth mode is observed right from the initial growth stage, which warrants precise control of the sample thickness beyond three monolayer and homogeneous surface morphology across the entire wafer. Moreover, the presence of the Coulomb interaction at the CrTe2/Al2O3 interface plays an important role in tailoring the anomalous Hall response, and the structural optimization of the CrTe2-based spin-orbit torque device leads to a substantial switching power reduction by 54%. The results may lay out a general framework for the design of energy-efficient spintronics based on configurable vdW FMs.

Imaging nucleation and propagation of pinned domains in few-layer Fe5–xGeTe2

ACS Nano American Chemical Society 17:17 (2023) 16879-16885

Authors:

Michael Hoegen, Ryuji Fujita, Anthony KC Tan, Alexandra Geim, Michael Pitts, Zhengxian Li, Luciano Stefan, Thorsten Hesjedal, Mete Atatuere

Abstract:

Engineering nontrivial spin textures in magnetic van der Waals materials is highly desirable for spintronic applications based on hybrid heterostructures. The recent observation of labyrinth and bubble domains in the near room-temperature ferromagnet Fe5–xGeTe2 down to a bilayer thickness was thus a significant advancement toward van der Waals-based many-body physics. However, the physical mechanism responsible for stabilizing these domains remains unclear and requires further investigation. Here, we combine cryogenic scanning diamond quantum magnetometry and field reversal techniques to elucidate the high-field propagation and nucleation of bubble domains in trilayer Fe5–xGeTe2. We provide evidence of pinning-induced nucleation of magnetic bubbles and further show an unexpectedly high layer-dependent coercive field. These measurements can be easily extended to a wide range of magnetic materials to provide valuable nanoscale insight into domain processes critical for spintronic applications.

Covalency, correlations, and interlayer interactions governing the magnetic and electronic structure of Mn3Si2Te6

Physical Review B American Physical Society (APS) 108:5 (2023) 54419

Authors:

Chiara Bigi, Lei Qiao, Chao Liu, Paolo Barone, Monica Ciomaga Hatnean, Gesa-R Siemann, Barat Achinuq, Daniel Alexander Mayoh, Giovanni Vinai, Vincent Polewczyk, Deepak Dagur, Federico Mazzola, Peter Bencok, Thorsten Hesjedal, Gerrit van der Laan, Wei Ren, Geetha Balakrishnan, Silvia Picozzi, Phil DC King

Probing the Local Electronic Structure in Metal Halide Perovskites through Cobalt Substitution

Small Methods Wiley 7:6 (2023)

Authors:

Amir A Haghighirad, Matthew T Klug, Liam Duffy, Junjie Liu, Arzhang Ardavan, Gerrit Laan, Thorsten Hesjedal, Henry J Snaith