Abstract
Single-molecule magnets (SMMs) are among the most promising building blocks for future magnetic data storage or quantum computing applications, owing to magnetic bistability and long magnetic relaxation times. The practical device integration requires realization of 2D surface assemblies of SMMs, where each magnetic unit shows magnetic relaxation being sufficiently slow at application-relevant temperatures. Using X-ray absorption spectroscopy and X-ray magnetic circular dichroism, it is shown that sub-monolayers of Dy2 @C80 (CH2 Ph) dimetallofullerenes prepared on graphene by electrospray deposition exhibit magnetic behavior fully comparable to that of the bulk. Magnetic hysteresis and relaxation time measurements show that the magnetic moment remains stable for 100 s at 17 K, marking the blocking temperature TB(100) , being not only in excellent agreement with that of the bulk sample but also representing by far the highest one detected for a surface-supported single-molecule magnet. The reported findings give a boost to the efforts to stabilize and address the spin degree of freedom in molecular magnets aiming at the realization of SMM-based spintronic units.
Highlights
Benchmark measurements during the last years demonstrating magnetic bistability of surface-adsorbed SMMs haveSingle-molecule magnets (SMMs) belong to the smallest units been reported on substrates, where molecules are electronically wherein magnetic moments can remain intrinsically stable on weakly coupled to – TbPc2 on HOPG,[24] on MgO/Ag(100)[25] time scales required for possible technological applications.[1,2,3] and on graphene/SiC,[26] pushing the blocking temperatureIntense research in the field of nanomagnetism within the (TB) limit up to 9 K
The Dy2@C80(CH2Ph) molecules deposited by the electrospray deposition method are organized into islands as shown by low-temperature scanning tunneling microscopy (STM) imaging. We explore their magnetic properties by means of X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) measurements
The sub-monolayer shows a hysteresis curve that closes around 20 K, twice the value measured on surface-adsorbed molecular magnets so far
Summary
Benchmark measurements during the last years demonstrating magnetic bistability of surface-adsorbed SMMs have. DySc2N@C80 mono last decade has further boosted technologically relevant perfor- layers on Au(111)[27] recently showed a hysteresis opening at mance indicators, resulting in SMMs magnetically stable above temperatures up to 10 K. In this work we provide experimental evidence on outstanding slow magnetic relaxation in Dy2@C80(CH2Ph) sub-mono layers on a graphene/Ir(111) surface. Blocking temperature value similar to that of the bulk, and representing the highest reported one for a molecular magnet on a surface.[25,26,27]
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