Uniaxial magnetic anisotropy and type- <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>x</mml:mi> <mml:mo>/</mml:mo> <mml:mi>y</mml:mi> </mml:math> current-induced magnetization switching in oblique-angle-deposited

Planar current-induced magnetization switching (CIMS) driven by spin-orbit torque (SOT) requires an in-plane uniaxial magnetic anisotropy (UMA), which can be induced by oblique-angle sputter deposition of the heavy-metal underlayer in heavy-metal/ferromagnet heterostructures. To enhance the SOT efficiency, we employ trilayer heterostructures of ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>Ta</a:mi> </a:math> or <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mrow> <c:mrow> <c:mi mathvariant="normal">W</c:mi> </c:mrow> </c:mrow> </c:math> )/ <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"> <f:mi>Co</f:mi> </f:math> - <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"> <h:mi>Fe</h:mi> </h:math> - <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"> <j:mrow> <j:mrow> <j:mi mathvariant="normal">B</j:mi> </j:mrow> </j:mrow> </j:math> / <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:mi>Pt</m:mi> </m:math> , where the <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"> <o:mi>Co</o:mi> </o:math> - <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"> <q:mi>Fe</q:mi> </q:math> - <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"> <s:mrow> <s:mrow> <s:mi mathvariant="normal">B</s:mi> </s:mrow> </s:mrow> </s:math> layer exhibits a UMA of 50 mT at a 2-nm thickness of <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"> <v:mi>Ta</v:mi> </v:math> or <x:math xmlns:x="http://www.w3.org/1998/Math/MathML" display="inline"> <x:mrow> <x:mrow> <x:mi mathvariant="normal">W</x:mi> </x:mrow> </x:mrow> </x:math> . The magnetization reversal in Hall-bar devices is detected through unidirectional spin-Hall magnetoresistance for the type- <ab:math xmlns:ab="http://www.w3.org/1998/Math/MathML" display="inline"> <ab:mi>y</ab:mi> </ab:math> geometry (easy-axis transverse to current) and planar Hall measurements for the type- <cb:math xmlns:cb="http://www.w3.org/1998/Math/MathML" display="inline"> <cb:mi>x</cb:mi> </cb:math> geometry (easy-axis parallel to current). Both configurations exhibit CIMS with submicrosecond current pulses, reaching switching-current densities as low as <eb:math xmlns:eb="http://www.w3.org/1998/Math/MathML" display="inline"> <eb:mn>2</eb:mn> <eb:mo>×</eb:mo> <eb:msup> <eb:mn>10</eb:mn> <eb:mn>11</eb:mn> </eb:msup> <eb:mspace width="0.2em"/> <eb:mrow> <eb:mi mathvariant="normal">A</eb:mi> </eb:mrow> <eb:mo>/</eb:mo> <eb:msup> <eb:mrow> <eb:mi mathvariant="normal">m</eb:mi> </eb:mrow> <eb:mn>2</eb:mn> </eb:msup> </eb:math> for a <jb:math xmlns:jb="http://www.w3.org/1998/Math/MathML" display="inline"> <jb:mrow> <jb:mrow> <jb:mi mathvariant="normal">W</jb:mi> </jb:mrow> </jb:mrow> </jb:math> (4 nm)/ <mb:math xmlns:mb="http://www.w3.org/1998/Math/MathML" display="inline"> <mb:mi>Co</mb:mi> </mb:math> - <ob:math xmlns:ob="http://www.w3.org/1998/Math/MathML" display="inline"> <ob:mi>Fe</ob:mi> </ob:math> - <qb:math xmlns:qb="http://www.w3.org/1998/Math/MathML" display="inline"> <qb:mrow> <qb:mrow> <qb:mi mathvariant="normal">B</qb:mi> </qb:mrow> </qb:mrow> </qb:math> (1.4 nm)/ <tb:math xmlns:tb="http://www.w3.org/1998/Math/MathML" display="inline"> <tb:mi>Pt</tb:mi> </tb:math> (2 nm) stack with a UMA of 146 mT. Macrospin simulations reproduce the type- <vb:math xmlns:vb="http://www.w3.org/1998/Math/MathML" display="inline"> <vb:mi>y</vb:mi> </vb:math> switching as coherent magnetization rotation, whereas the type- <xb:math xmlns:xb="http://www.w3.org/1998/Math/MathML" display="inline"> <xb:mi>x</xb:mi> </xb:math> devices switch at much lower currents than predicted, indicating that nucleation and domain-wall propagation dominate reversal in this geometry. Our results show that combining oblique-angle deposition with easy-axis engineering enables deterministic, field-free switching, paving the way for future low-power spintronic devices.