AI Article Synopsis
- Single-crystalline FeTe with an orthorhombic structure was synthesized using chemical vapor transport and showed multiple magnetic phase transitions when cooled down from room temperature.
- Transitions from paramagnetic to antiferromagnetic and then to ferromagnetic states were noted at specific temperatures for both in-plane and out-of-plane orientations, with strong uniaxial magnetic anisotropy observed due to octahedron distortion.
- A notable negative volume expansion and anomalies in temperature-dependent resistance indicated a semiconductor-to-metallic transition near the AFM-FM transition, with structural, vibrational, and transport properties showing sensitivity to these phase changes.
Article Abstract
Single-crystalline FeTe in marcasite phase with orthorhombic structure was prepared via chemical vapor transport. Cooling FeTe single crystals from room temperature down to [Formula: see text], multiple magnetic phase transitions were observed. Paramagnetic (PM) to antiferromagnetic (AFM) and then to ferromagnetic (FM) occurred at [Formula: see text] and [Formula: see text] for in-plane, [Formula: see text] and [Formula: see text] for out-of-plane, respectively. A strong uniaxial magnetic anisotropy was found due to FeTe octahedron distortion and structural modulation in FM region. The novel negative volume expansion (NVE) initiated in the vicinity of AFM to FM transition. An abrupt frequency shift of the most intense mode at [Formula: see text] and evolution of the Te-Te stretching mode near [Formula: see text], corresponding to the phase transition from AFM to FM were observed. The temperature-dependent resistance revealed an anomaly (semiconductor to metallic transition) around AFM-FM transition, which can easily be suppressed and move to high temperature by the applied magnetic field. The results from XRD, Raman and resistivity indicated that the structural parameters, vibration frequency and transport are sensitive to the phase transition from AFM to FM. The nature of direct band gap with [Formula: see text] was identified through UV-Vis-NIR spectrum of FeTe single crystals at room temperature.
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| http://dx.doi.org/10.1088/1361-648X/ab4b72 | DOI Listing |
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