Magnetic domain structures in ultrathin Bi₂Te₃/CrTe₂ heterostructures

【摘要】 Chromium tellurium compounds are important two-dimensional van der Waals ferromagnetic materials with high Curie temperature and chemical stability in air,which is promising for applications in spintronic devices.Here,highquality spin-orbital-torque（SOT） device,Bi₂Te₃/CrTe₂ heterostructure was epitaxially grown on Al₂O₃（0001） substrates.Anomalous Hall measurements indicate the existence of strong ferromagnetism in this device with the CrTe₂ thickness down to 10 nm.In order to investigate its micromagnetic structure,cryogenic magnetic force microscope（MFM） was utilized to measure the magnetic domain evolutions at various temperatures and magnetic fields.The virgin domain state of the device shows a worm-like magnetic domain structure with the size around 0.6 μm-0.8 μm.Larger irregular-shape magnetic domains（> 1 μm） can be induced and pinned,after the field is increased to coercive field and ramped back to low fields.The temperature-dependent MFM signals exhibit a nice mean-field-like ferromagnetic transition with Curie temperature around 201.5 K,indicating a robust ferromagnetic ordering.Such a device can be potentially implemented in future magnetic memory technology.更多还原

【Abstract】 Chromium tellurium compounds are important two-dimensional van der Waals ferromagnetic materials with high Curie temperature and chemical stability in air,which is promising for applications in spintronic devices.Here,highquality spin-orbital-torque（SOT） device,Bi₂Te₃/CrTe₂ heterostructure was epitaxially grown on Al₂O₃（0001） substrates.Anomalous Hall measurements indicate the existence of strong ferromagnetism in this device with the CrTe₂ thickness down to 10 nm.In order to investigate its micromagnetic structure,cryogenic magnetic force microscope（MFM） was utilized to measure the magnetic domain evolutions at various temperatures and magnetic fields.The virgin domain state of the device shows a worm-like magnetic domain structure with the size around 0.6 μm-0.8 μm.Larger irregular-shape magnetic domains（> 1 μm） can be induced and pinned,after the field is increased to coercive field and ramped back to low fields.The temperature-dependent MFM signals exhibit a nice mean-field-like ferromagnetic transition with Curie temperature around 201.5 K,indicating a robust ferromagnetic ordering.Such a device can be potentially implemented in future magnetic memory technology.更多还原