ABSTRACT
Quantum sensing is one of the frontier research area that harnesses the principles of quantum mechanics to achieve ultra-sensitive and precise measurements beyond classical limits. Solid-state defect centers, such as negatively charged nitrogen-vacancy (NV−) centers in diamond, are promising quantum sensors for detecting various physical quantities including magnetic field, temperature and pressure. The Optically Detected Magnetic Resonance (ODMR) spectrum of NV− center is utilized for magnetic field sensing, which can be used to analyze the magnetism of novel materials, including Meissner effect of superconductors.
The superconductivity in 2D materials has attracted much attention in recent years. In iron-based superconductors, iron telluride (FeTe) has unconventional superconducting properties. When forming heterostructures with other materials such as Bi2Te3 and MnTe, the system shows superconductivity and exhibits Meissner effect in cryogenic temperature.
In this thesis, we use NV− center in nano-diamond particles as quantum sensors to detect superconductivity of FeTe/layered-MnTe heterostructure under cryogenic temperature. The ODMR spectrum indicates that there is absence of Meissner effect detected by NV− centers. On the contrary, the sample may exist a ferromagnetic phase transition under cryogenic temperature, with the local magnetic field intensity increased at lower temperature. We further exclude the influence of vibration and heater for this phenomenon, and analyzed several aspects that can be improved to sense superconductivity of this sample and other similar 2D materials.