[22a-B201-1~11] 10.1 Emerging materials in spintronics and magnetics (including fabrication and characterization methodologies)

▲ [22a-B201-4] The anomalous Hall effect of MBE-grown van der Waals ferromagnet CrTe₂

〇Yujun Wang¹, Masashi Kawaguchi¹, Masamitsu Hayashi¹ (1.The University of Tokyo)

Keywords:Anomalous Hall effect, CrTe2, Molecular beam epitaxy

We conducted a systematic study on the growth and magneto-transport properties of CrTe₂ thin films. CrTe₂ is composed of layers that are bonded via the van der Waals interaction. The Cr atoms possess magnetic moment that are exchange coupled ferromagnetically. Studies have shown that the Curie temperature of CrTe₂ can exceed room temperature. We have grown CrTe₂ thin films using molecular beam epitaxy (MBE). The film structure is characterized by RHEED and X-ray diffraction (XRD). The RHEED patterns show sharp streaks during the growth of the film, indicating an atomic-scale smooth surface. Typical Bragg diffraction peaks associated with the hexagonal (0001) planes are observed in XRD spectrum. The position and amplitude of the peaks are in good agreement with tabulated data in the database, suggesting successful preparation of high quality CrTe₂ films.
The magneto-transport properties of the films were studied using micro-fabricated Hall bars. The anomalous Hall resistance R_AH is measured against the out of plane magnetic field. A square hysteresis loop is observed at low temperature, indicating the existence of the ferromagnetic phase. The Curie temperature is ~200 to ~250 K, which depends on the deposition condition. R_AH is found to vary with the measurement temperature. Interestingly, the sign of R_AH changes as the temperature is increased. In addition to the anomalous Hall effect, we find hump-like structure in the R_AH vs. field loop, similar to that observed in systems that exhibit the topological Hall effect. Details of these Hall resistances will be discussed in the presentation.