Low-Frequency Electronic Noise Characteristics of Vertical Quasi-Two-Dimensional Antiferromagnetic Semiconductor Devices

A new frontier in the search for the next-generation electronic, photonic, and spintronic devices is quasi 2D films of transition-metal phospho-trichalcogenides (MPX₃) where “M” is a transition metal and “X” is a chalcogen [1]. Recent studies have reported that MPX₃ structures are one of rare few-layer van der Waals (vdW) materials with stable intrinsic antiferromagnetism (AFM) even at mono- and few-layer thicknesses. The diverse properties of layered MPX₃ materials, tunable by proper selection and combination of the “M” and “X” elements make them an interesting platform for investigating novel low-dimensional device functionalities. The existence of weak vdW bonds between the MPX₃ layers allows one to scale them conveniently to individual atomic planes. The “M” element determines the AFM spin ordering. While FePS₃ shows an Ising-type phase transition at the Néel temperature (<i>T_N</i>), NiPS₃ follows XY-phase transitions, respectively. MPX₃ structures are semiconductors in nature and variation in the metal element modifies their bandgap from ~1.3 eV to ~3.5 eV. The latter opens up unique opportunities to design novel electronic and magnonic nanodevices suitable for optoelectronic and spintronic applications. However, the data on the electron transport properties and their interaction with spin ordering in these structures is scarce and requires detailed investigations. MPX₃ materials are highly resistive making electron transport measurements a formidable challenge in conventional lateral device structures. To overcome this challenge, we fabricated vertical <i>h</i>-BN/MPX₃ heterostructure devices with different MPX₃ components hosting various AFM spin orderings. In this presentation, we report the results of our temperature-dependent cross-plane electrical transport and noise measurements. The low-frequency noise spectroscopy was used to detect the magnetic phase transitions [2]. In vertical <i>h</i>-BN/FePS₃ devices with the active layer characterized by the Ising-type spin order, we observed a combination of two Lorentzian bulges appearing in the overall <i>1/f</i> noise envelope at or close to <i>T_N</i>. These two features were attributed to the generation-recombination (G-R) and magnetic phase transition. The noise measurements of the vertical devices with both FePS₃ and NiPS₃ active layers, characterized by the Ising and XY AFM spin orders respectively, revealed mulitple noise peaks near the magnetic phase transitions. The intensity of the noise peaks in NiPS₃ was significantly higher than that in the FePS₃ device. The comparison of noise characteristics for devices fabricated with two materials of different AFM spin ordering shows a strong dependence of noise on the particular magnetic spin direction and suggests a strong interplay of the magnetic and electrical properties in these AFM materials.<br/><br/>F.K. and A.B.B. acknowledge funding from the National Science Foundation (NSF), Division of Material Research (DMR) via the project No. 2205973 "Controlling Electron, Magnon, and Phonon States in Quasi 2D Antiferromagnetic Semiconductors for Enabling Novel Device Functionalities.”<br/><br/>[1] F. Kargar, E. A. Coleman, S. Ghosh, J. Lee, M. J. Gomez, Y. Liu, A. S. Magana, Z. Barani, A. Mohammadzadeh, B. Debnath, R. B. Wilson, R. K. Lake, and A. A. Balandin, "Phonon and thermal properties of quasi-two-dimensional FePS₃ and MnPS₃ antiferromagnetic semiconductors," ACS Nano, 14, 2, 2424-2435 (2020).<br/>[2] S. Ghosh, F. Kargar, A. Mohammadzadeh, S. Rumyantsev, and A. A. Balandin, “Low-frequency electronic noise spectroscopy of quasi 2D van der Waals antiferromagnetic semiconductors,” Adv. Electron. Mater., 2100408 (2021).