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Researchers discovered that the magnetic material alpha-MnTe exhibits an exceptionally large spontaneous Kerr rotation effect of up to 1500 radians at telecommunication wavelengths (1550 nm), which begins precisely at its magnetic ordering temperature of 307 K. The study reveals that this giant magneto-optical response is not solely due to the material's altermagnetic ordering, but is strongly influenced by carrier self-doping and sample conductivity, as evidenced by the effect appearing in distinct patches that correlate with electrical conductivity variations.
Why it matters
This finding enables practical optical readout methods for altermagnetic spintronic devices operating at telecommunication wavelengths, potentially advancing ultrafast, stray-field-free magnetic memory and computing technologies. The discovery that material doping controls the magneto-optical response provides a pathway for engineering enhanced effects in future devices.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
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Abstract: Altermagnetism, a third class of collinear magnetism with spin-split bands and vanishing net magnetization, has emerged in hexagonal {alpha}-MnTe, a promising platform for ultrafast, stray-field-free spintronics. Whether MnTe’s macroscopic symmetry-breaking signatures reflect ideal altermagnetic order or are activated by defects remains open. Here we report giant spontaneous Kerr rotations of up to 1500 rad in {alpha}-MnTe single crystals at the telecommunication wavelength of 1550 nm, onsetting precisely at the N’eel temperature TN = 307 K. The signal appears in disjoint macroscopic patches whose amplitude tracks the sample conductivity, and a hole-conducting {alpha}-MnTe film reproduces this response together with an anomalous Hall effect. Within a single crystal, Kerr-active regions are optically distinct from their Kerr-silent surroundings in co-registered reflection maps. These observations indicate that carrier self-doping, rather than ideal altermagnetic order alone, governs the giant magneto-optical response, and establish telecom-wavelength Kerr imaging as a practical readout for altermagnetic spintronics.
Source: Giant spontaneous Kerr effect and its self-doping dependence in altermagnetic MnTe