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On 18 June, the VNUHCM–University of Science (HCMUS) convened an evaluation committee for a VNUHCM-level science and technology project entitled “Research on the anomalous Hall effect of ferromagnetic materials using first-principles simulation,” chaired by Dr Trịnh Thị Lý, the project examines the control mechanisms of the anomalous Hall effect within ferromagnetic materials, aiming to provide a scientific foundation for designing materials applicable to the field of spintronics.

The anomalous Hall effect represents a crucial phenomenon in magnetic materials, holding significant potential for application in next-generation spintronic devices. A primary area of current academic interest involves identifying mechanisms capable of modulating and enhancing anomalous Hall conductivity (AHC).

Within the framework of this research, the investigators focused on investigating hexagonal close-packed cobalt (hcp-Co) to evaluate how elastic strain influences the electronic characteristics and transport properties of the material. By combining the first-principles simulation method (ab initio) with a tight-binding computational model, the research team analysed the quantum physical mechanisms associated with variations in anomalous Hall conductivity under mechanical strain.

The findings demonstrate that the anomalous Hall conductivity of hcp-Co can be adjusted via elastic strain within a range from -2% to +2%. The AHC value reaches a maximum at a compressive strain of -0.5%, exhibiting a variation of up to 24% compared to the pristine state. Computational results indicate that this modification relates to the shift of energy band anti-crossing points closer to the Fermi level, which alters the Berry curvature distribution and directly affects the anomalous Hall conductivity of the material.

Alongside these scientific outcomes, the project successfully delivered the academic products and training objectives originally set forth. The research group developed an anomalous Hall conductivity (AHC) calculation module integrated into the bphase programme, published a scientific paper entitled “Tuning the Anomalous Hall Conductivity of hcp-Cobalt by Constant-Volume Biaxial Strain” in a journal within the IEEJ Transactions system, and contributed to postgraduate education by supervising one Master’s student to completion.

The outcomes of this research contribute to the scientific framework regarding the ability to control the anomalous Hall effect via mechanical strain in ferromagnetic materials. Furthermore, the work establishes an analytical approach for investigating and optimising magnetic materials to serve spintronics research.

The evaluation committee agreed that the project fulfilled all registered research contents and deliverables, whilst acknowledging the achievements in elucidating the physical mechanisms of the anomalous Hall effect in ferromagnetic materials. The committee members unanimously approved the evaluation results of the project.