arXiv subjects

Yihui Jiang

Publications and source records attributed to Yihui Jiang.

3 recordsLinked to original sources

arXiv2026

Melting behavior and dynamical properties of Cr2Ge2Te6 phase-change material

Cr2Ge2Te6 (CrGT) is known as an intrinsic ferromagnetic semiconductor and a promising candidate for phase-change memory applications. In amorphous CrGT, Cr atoms form non-defective octahedral motifs with Te atoms, similar to those in the crystalline phase. The abundance of Cr[Te6] octahedra is regarded as the key structural factor in reducing the resistance drift coefficient of amorphous CrGT. However, the stage at which these octahedra emerge during melt-quench amorphization remains unclear. Here, we present ab initio molecular dynamics (AIMD) simulations to model the melting process of crystalline CrGT and to investigate the dynamical properties of liquid and supercooled liquid CrGT in detail. Upon heating, Ge atoms are observed to leave their lattice sites earlier than Cr and Te atoms, diffusing into the van der Waals gap and initiating the collapse of the layered structure. The Cr[Te6] octahedra are more robust, maintaining their structural pattern up to 1400 K despite continuous rupture and re-formation of Cr-Te bonds. At higher temperatures, Cr and Te atoms start to migrate independently. In supercooled liquid CrGT at 550 K, most Cr-centered octahedra remain intact, with only limited Cr-Te bond breaking. The collective motion of these octahedra in this temperature regime helps explain why crystallization in CrGT devices can be accomplished in tens of nanoseconds.

cond-mat.mtrl-sci↗

arXiv2025

Spin glass behavior in amorphous CrSiTe3 alloy

Owing to the intrinsically high crystallization temperatures, layered phase-change materials, such as CrGeTe3 and InGeTe3, are attracting attention for embedded memory applications, In addition to the electrical contrast, a major change in magnetic properties is observed in CrGeTe3 upon switching from the crystalline to the amorphous state. In this work, we report a combined ab initio modeling and magnetic characterization study on the isostructural silicon parent compound of CrGeTe3, namely, CrSiTe3. Amorphous CrSiTe3 has similar structural properties to amorphous CrGeTe3; however, it shows a smaller energy difference between the ferromagnetic configuration and the random magnetic configuration, indicating a high probability of spin glass formation. Indeed, direct-current and alternating-current magnetic measurements show that the coercive force of amorphous CrSiTe3 is higher than that of amorphous CrGeTe3. Therefore, the pinning effect of spins is enhanced in amorphous CrSiTe3, leading to a more robust spin glass state with a higher freezing temperature. The large magnetic contrast between the amorphous and crystalline phase could make CrSiTe3 a potential candidate for phase-change magnetic switching applications.

cond-mat.mtrl-sci↗

arXiv2024

Ab initio investigation of layered TMGeTe3 alloys for phase-change applications

Chalcogenide phase-change materials (PCMs) are one of the most mature candidates for next-generation memory technology. Recently, CrGeTe3 (CrGT) emerged as a promising PCM due to its enhanced amorphous stability and fast crystallization for embedded memory applications. The amorphous stability of CrGT was attributed to the complex layered structure of the crystalline motifs needed to initiate crystallization. A subsequent computational screening work identified several similar compounds with good thermal stability, such as InGeTe3, CrSiTe3 and BiSiTe3. Here, we explore substitution of Cr in CrGT with other 3d metals, and predict four additional layered alloys to be dynamically stable, namely, ScGeTe3, TiGeTe3, ZnGeTe3 and MnGeTe3. Thorough ab initio simulations performed on both crystalline and amorphous models of these materials indicate the former three alloys to be potential PCMs with sizable resistance contrast. Furthermore, we find that crystalline MnGeTe3 exhibits ferromagnetic behavior, whereas the amorphous state probably forms a spin-glass phase. This makes MnGeTe3 a promising candidate for magnetic phase-change applications.

cond-mat.mtrl-sci↗