Low-noise anisotropic magnetoresistance sensing at human body temperature: unveiling the optimal doping in La1−xSrxMnO3 films

Low-field anisotropic magnetoresistance (AMR) sensors based on epitaxial La1−xSrxMnO3 (LSMO) thin films combine ultra-low noise, good interplay between sensitivity and detectivity, and straightforward fabrication, offering a compelling alternative to giant and tunnel magnetoresistance technologies. Here, by tuning Sr doping (x = 0.15–0.45) of LSMO films grown epitaxially on 4° miscut (001)-oriented SrTiO3 substrates, we achieve fine control of performance parameters tailored to match biomedical environments operating at tightly regulated temperatures. We resort to shape-induced uniaxial magnetic anisotropy and Wheatstone bridge structures to suppress noise and isolate the AMR signal. Temperature-dependent characterization reveals that devices with x = 0.35 deliver optimal sensitivity and lowest electronic noise at 310 K (human body temperature), highlighting their strong potential for biomedical sensing applications.