Magnetic force microscopy revealing long range molecule impact on magnetic tunnel junction based molecular spintronics devices

The most outstanding feature of scanning force microscopy (SFM) is its capability to detect various different short and long range interactions. In particular, magnetic force microscopy (MFM) is used to characterize the domain configuration in ferromagnetic materials such as thin films grown by physical techniques or ferromagnetic nanostructures. It is a usual procedure to separate the topography and the magnetic signal by scanning at a lift distance of 25–50 nm such that the long range tip–sample interactions dominate. Nowadays, MFM is becoming a valuable technique to detect weak magnetic fields arising from low dimensional complex systems such as organic nanomagnets, superparamagnetic nanoparticles, carbon-based materials, etc. In all these cases, the magnetic nanocomponents and the substrate supporting them present quite different electronic behavior, i.e., they exhibit large surface potential differences causing heterogeneous electrostatic interaction between the tip and the sample that could be interpreted as a magnetic interaction. To distinguish clearly the origin of the tip–sample forces we propose to use a combination of Kelvin probe force microscopy (KPFM) and MFM. The KPFM technique allows us to compensate in real time the electrostatic forces between the tip and the sample by minimizing the electrostatic contribution to the frequency shift signal. This is a great challenge in samples with low magnetic moment. In this work we studied an array of Co nanostructures that exhibit high electrostatic interaction with the MFM tip. Thanks to the use of the KPFM/MFM system we were able to separate the electric and magnetic interactions between the tip and the sample.

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Room Temperature Current Suppression on Magnetic Tunnel Junction Based Molecular Spintronics Devices

MRS Proceedings ◽

10.1557/opl.2013.952 ◽

2013 ◽

Vol 1507 ◽

Author(s):

Pawan Tyagi

Keyword(s):

Tunnel Junction ◽

Exchange Coupling ◽

Room Temperature ◽

Spin Transport ◽

Magnetic Tunnel Junction ◽

Test Bed ◽

Force Microscopy ◽

Molecular Spintronics ◽

Ferromagnetic Electrodes ◽

Strong Exchange

ABSTRACTMolecular conduction channels between two ferromagnetic electrodes can produce strong exchange coupling and dramatic effect on the spin transport, thus enabling the realization of novel logic and memory devices. To realize such device, we produced Multilayer Edge Molecular Spintronics Devices (MEMSDs) by bridging the organometallic molecular clusters (OMCs) across a ∼2 nm thick insulator of a magnetic tunnel junction (MTJ), along its exposed side edges. These MEMSDs exhibited unprecedented increase in exchange coupling between ferromagnetic films and dramatic changes in the spin transport. This paper focuses on the dramatic current suppression phenomenon exhibited by MEMSDs at room temperature. In the event of current suppression, the effective MEMESDs’ current reduced by as much as six orders in magnitude as compared to the leakage current level of a MTJ test bed. Current suppression phenomenon was found to be associated with the equally dramatic changes in the MTJ test beds due to OMCs. Role of OMC in changing MTJ test bed properties was determined by the three different types of magnetic characterizations: SQUID Magnetometer, Ferromagnetic Resonance, and Magnetic Force Microscopy. Observation of current suppression by independent research groups and supporting studies on similar systems will be crucially important to unequivocally establish the utility of MEMSD approach.

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Bimodal magnetic force microscopy: Separation of short and long range forces

Applied Physics Letters ◽

10.1063/1.3126521 ◽

2009 ◽

Vol 94 (16) ◽

pp. 163118 ◽

Cited By ~ 46

Author(s):

Jason W. Li ◽

Jason P. Cleveland ◽

Roger Proksch

Keyword(s):

Long Range ◽

Magnetic Force Microscopy ◽

Magnetic Force ◽

Force Microscopy

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Molecule Induced Strong Coupling between Ferromagnetic Electrodes of a Molecular Spintronics Device

Materials Science Forum ◽

10.4028/www.scientific.net/msf.736.32 ◽

2012 ◽

Vol 736 ◽

pp. 32-54 ◽

Cited By ~ 6

Author(s):

Pawan Tyagi

Keyword(s):

Tunnel Junction ◽

Magnetic Tunnel Junction ◽

Molecular Complexes ◽

Ferromagnetic Material ◽

Molecular Magnet ◽

Force Microscopy ◽

Molecular Spintronics ◽

Ferromagnetic Electrodes ◽

Spintronics Device ◽

Magnetic Hardness

Utilizing molecules for tailoring the exchange coupling strength between ferromagnetic electrodes can produce novel metamaterials and molecular spintronics devices (MSD). A practical way to produce such MSD is to connect the molecular channels to the electrodes of a magnetic tunnel junction (MTJ). This paper discusses the dramatic changes in the properties of MTJ testbed of a MSD due to molecular device elements with a net spin state. When organometallic molecular complexes (OMCs) were bridged across the insulator along the exposed side edges, a MTJ testbed exhibited entirely different magnetic response in magnetization, ferromagnetic resonance and magnetic force microscopy studies. OMCs only affected the ferromagnetic material when it was serving as the electrode of a tunnel junction. Molecule produced the strongest effect on the MTJ with electrodes of dissimilar magnetic hardness. This study encourages the validation of this work and exploration of similar observations with the other combinations MTJs and molecules, like single molecular magnet, porphyrin, and molecular clusters.

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Study of MFM Application in Semiconductor Failure Analysis

ISTFA 2004: Conference Proceedings from the 30th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2004p0353 ◽

2004 ◽

Author(s):

Way-Jam Chen ◽

Lily Shiau ◽

Ming-Ching Huang ◽

Chia-Hsing Chao

Keyword(s):

Magnetic Field ◽

Failure Analysis ◽

Magnetic Force Microscopy ◽

Magnetic Force ◽

Current Flow ◽

Force Microscopy ◽

The Magnetic Field ◽

A Current

Abstract In this study we have investigated the magnetic field associated with a current flowing in a circuit using Magnetic Force Microscopy (MFM). The technique is able to identify the magnetic field associated with a current flow and has potential for failure analysis.

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Magnetic Force Microscopy: Comparison and Validation of Different Magnetic Force Microscopy Calibration Schemes (Small 11/2020)

Small ◽

10.1002/smll.202070058 ◽

2020 ◽

Vol 16 (11) ◽

pp. 2070058

Author(s):

Héctor Corte‐León ◽

Volker Neu ◽

Alessandra Manzin ◽

Craig Barton ◽

Yuanjun Tang ◽

...

Keyword(s):

Magnetic Force Microscopy ◽

Magnetic Force ◽

Force Microscopy

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Magnetic Domain Observation on Melt-Spun Nd-Fe-B Ribbons Using Magnetic Force Microscopy

MRS Proceedings ◽

10.1557/proc-577-241 ◽

1999 ◽

Vol 577 ◽

Author(s):

A. Gavrin ◽

C. Sellers ◽

S.H. Liouw

Keyword(s):

Magnetic Force Microscopy ◽

Magnetic Force ◽

Magnetic Measurements ◽

Magnetic Domain ◽

Domain Size ◽

High Coercivity ◽

Uniform Domain ◽

Cross Sectional ◽

Force Microscopy ◽

Melt Spun

ABSTRACTWe have used Magnetic Force Microscopy (MFM) to study the magnetic domain structures of melt-spun Nd-Fe-B ribbons. The ribbons are commercial products (Magnequench International, Inc. MQP-B and MQP-B+) with a thickness of approximately 20 microns. These materials have identical composition, Nd12.18B5.36Fe76.99Co5.46, but differ in quenching conditions. In order to study the distribution of domain sizes through the ribbon thickness, we have prepared cross-sectional samples in epoxy mounts. In order to avoid artifacts due to tip-sample interactions, we have used high coercivity CoPt coated MFM tips. Our studies show domain sizes typically ranging from 50-200 nm in diameter. This is in agreement with studies of similar materials in which domains were investigated in the plane of the ribbon. We also find that these products differ substantially in mean domain size and in the uniformity of the domain sizes as measured across the ribbon. While the B+ material shows nearly uniform domain sizes throughout the cross section, the B material shows considerably larger domains on one surface, followed by a region in which the domains are smaller than average. This structure is presumably due to the differing quench conditions. The region of coarse domains varies in thickness, disappearing in some areas, and reaching a maximum thickness of 2.75 µm in others. We also describe bulk magnetic measurements, and suggest that.

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