Gate Voltage-Controlled Magnetic Anisotropy Effect on Pt-Porphyrin functionalized single-layer graphene

TL;DR

This study demonstrates that non-covalent functionalization of single-layer graphene with Pt-porphyrin significantly enhances spin-orbit coupling and enables voltage-controlled magnetic anisotropy, advancing low-power spintronic device development.

Contribution

It introduces a novel method to engineer large voltage-controlled magnetic anisotropy and spin-orbit coupling at graphene interfaces using Pt-porphyrin functionalization.

Findings

Achieved a VCMA coefficient of 375.6 fJ/(V-m).

Enhanced spin torque efficiency ({ heta}sh) by an order of magnitude.

Demonstrated reversible electric-field modulation of magnetic anisotropy.

Abstract

We report a novel approach to engineering large voltage-controlled magnetic anisotropy (VCMA) and enhanced spin-orbit coupling (SOC) at the interface of single-layer graphene (SLG) and NiFe (Py) through non-covalent functionalization with Platinum (II) 5,10,15,20-tetraphenyl porphyrin (Pt-porphyrin). Using chemical vapor deposition (CVD)-grown SLG, we demonstrate that Pt-porphyrin functionalization significantly increases the SOC and enables robust voltage modulation of interfacial magnetic anisotropy, as confirmed by spin-torque ferromagnetic resonance (ST-FMR) measurements. A substantial VCMA coefficient of 375.6 (fJ/(V-m)) is achieved, accompanied by an order-of-magnitude enhancement in spin torque efficiency ({\theta}sh) compared to pristine SLG. The resonance field exhibits a clear, reversible shift under applied gate voltage, confirming robust electric-field modulation of interfacial magnetic anisotropy. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) confirm the structural integrity and effective charge transfer at the functionalized interface. Electrical characterization of back-gated graphene field-effect transistors (GFETs) further reveals tunable electronic properties upon functionalization. Our results establish functionalized graphene/ferromagnet interfaces as a promising platform for low-power, voltage-controlled spintronic devices, paving the way for scalable, energy-efficient memory and logic technologies