Strong anisotropic Hall effect in single-crystalline CeMn2Ge2 with helical spin order

Abstract

The topological Hall effect (THE) is an emergent magnetotransport phenomena in noncollinear itinerant magnets, and has been extensively studied in magnetic materials hosting skyrmion lattices and geometrically frustrated lattices. To explore THE in materials with new nontrivial spin textures, we investigate the anisotropic Hall effect in a longitudinal conical-ordered magnet ${\mathrm{CeMn}}_{2}{\mathrm{Ge}}_{2}$ crystallized in ${\mathrm{ThCr}}_{2}{\mathrm{Si}}_{2}$-type structure, which has a spiral magnetic propagation vector along the $c$ axis and a helical component in the $ab$ plane. Magnetic susceptibility reveals it undergoes two magnetic transitions at \ensuremath{\sim}394 and \ensuremath{\sim}318 K; the latter corresponds to the antiferromagnetic to conical spin order transition in the magnetic Mn lattices. For applied field $({\ensuremath{\mu}}_{0}H)$ along the $c$ axis, ${\mathrm{CeMn}}_{2}{\mathrm{Ge}}_{2}$ exhibits conventional anomalous Hall effect with large intrinsic Hall conductivity ${\ensuremath{\sigma}}_{xy}^{\mathrm{int}}\ensuremath{\sim}276\phantom{\rule{0.28em}{0ex}}{\mathrm{\ensuremath{\Omega}}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$ but no THE responses. A large THE is realized as ${\ensuremath{\mu}}_{0}H$ is oriented within the $ab$ plane due to a field-induced noncoplanar spin texture with scalar spin chirality. Moreover, room temperature (RT) angle-dependent Hall effect measurements reveal the THE emerges when the field is applied nonparallel to the $c$ axis and it reaches maximal value for ${\ensuremath{\mu}}_{0}H$ when it is tilted close to the $ab$ plane with a canting angle of \ensuremath{\sim}15\ifmmode^\circ\else\textdegree\fi{}, at which large topological Hall conductivity of $\ensuremath{\sim}43\phantom{\rule{0.28em}{0ex}}{\mathrm{\ensuremath{\Omega}}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$ is detected. Our results demonstrate a RT anisotropic THE and its tunability by the application of a tilted magnetic field in conical-ordered magnets, making a step forward for designing spintronic devices based on THE.