Quantum metrology that employs weak values can potentially effectuate parameter estimation with an ultrahigh sensitivity and has been typically explored across quantum optics setups. Recognizing the importance of sensitive parameter estimation in the solid state, we propose a spintronic device platform to realize this. The setup estimates a very weak localized Zeeman splitting by exploiting a resonant tunneling-enhanced magnetoresistance readout. We establish that this paradigm offers nearly optimal performance with a quantum Fisher information enhancement of about ${10}^4$ times that of single high-transmissivity barriers. The obtained signal also offers a high sensitivity in the presence of dephasing effects typically encountered in the solid state. These results put forth definitive possibilities in harnessing the inherent sensitivity of resonant tunneling for solid-state quantum metrology with potential applications, especially, in the sensitive detection of small induced Zeeman effects in quantum material heterostructures.

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• Quantum Fisher information
• Quantum metrology
• Quantum optics
• Spintronics
• Tunneling magnetoresistance
• Weak values & weak measurements
• Zeeman effect
• Nonequilibrium Green's function