Dry-transferred CVD graphene for inverted spin valve devices

TL;DR

This paper demonstrates a dry transfer method for CVD graphene onto spin valve devices, achieving record high spin lifetimes and enabling advanced device geometries for spintronics and nanoelectronics.

Contribution

It introduces a van der Waals pickup transfer technique for CVD graphene, achieving high spin lifetimes and versatile device fabrication options.

Findings

Record high spin lifetime of 1.75 ns at room temperature.

Comparable performance to exfoliated graphene devices.

Dry transfer methods facilitate advanced device geometries.

Abstract

Integrating high-mobility graphene grown by chemical vapor deposition (CVD) into spin transport devices is one of the key tasks in graphene spintronics. We use a van der Waals pickup technique to transfer CVD graphene by hexagonal boron nitride (hBN) from the copper growth substrate onto predefined Co/MgO electrodes to build inverted spin valve devices. Two approaches are presented: (i) a process where the CVD-graphene/hBN stack is first patterned into a bar and then transferred by a second larger hBN crystal onto spin valve electrodes and (ii) a direct transfer of a CVD-graphene/hBN stack. We report record high spin lifetimes in CVD graphene of up to 1.75 ns at room temperature. Overall, the performances of our devices are comparable to devices fabricated from exfoliated graphene also revealing nanosecond spin lifetimes. We expect that our dry transfer methods pave the way towards more advanced device geometries not only for spintronic applications but also for CVD-graphene-based nanoelectronic devices in general where patterning of the CVD graphene is required prior to the assembly of final van der Waals heterostructures.