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Tunable room-temperature ferromagnet using an iron-oxide and graphene oxide nanocomposite.

Lin AL, Rodrigues JN, Su C, Milletari M, Loh KP, Wu T, Chen W, Neto AH, Adam S, Wee AT - Sci Rep (2015)

Bottom Line: Magnetic materials have found wide application ranging from electronics and memories to medicine.Not only can we tune its transition temperature in a wide range of temperatures around room temperature, but the magnetization can also be tuned from zero to 0.011 A m(2)/kg through an initialization process with two readily accessible knobs (magnetic field and electric current), after which the system retains its magnetic properties semi-permanently until the next initialization process.We construct a theoretical model to illustrate that this tunability originates from an indirect exchange interaction mediated by spin-imbalanced electrons inside the nanocomposite.

View Article: PubMed Central - PubMed

Affiliation: 1] NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore,28 Medical Drive, Singapore 117456 [2] Centre for Advanced 2D Materials and Graphene Research Centre, Faculty of Science, National University of Singapore, 6 Science Drive 2, Singapore 117546 [3] Department of Physics, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore 117542.

ABSTRACT
Magnetic materials have found wide application ranging from electronics and memories to medicine. Essential to these advances is the control of the magnetic order. To date, most room-temperature applications have a fixed magnetic moment whose orientation is manipulated for functionality. Here we demonstrate an iron-oxide and graphene oxide nanocomposite based device that acts as a tunable ferromagnet at room temperature. Not only can we tune its transition temperature in a wide range of temperatures around room temperature, but the magnetization can also be tuned from zero to 0.011 A m(2)/kg through an initialization process with two readily accessible knobs (magnetic field and electric current), after which the system retains its magnetic properties semi-permanently until the next initialization process. We construct a theoretical model to illustrate that this tunability originates from an indirect exchange interaction mediated by spin-imbalanced electrons inside the nanocomposite.

No MeSH data available.


Device’s electrical properties.(a) Device’s electrical resistance in terms of the Bext. (b) Ferromagnetic pinned electrodes response to an external magnetic field (bottom) and a blow up of the resistance data in the same field range (top). Measurements reveal two distinct jumps in resistance, one corresponding to the giant magnetoresistance and the other due to a ferromagnetic transition.
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f3: Device’s electrical properties.(a) Device’s electrical resistance in terms of the Bext. (b) Ferromagnetic pinned electrodes response to an external magnetic field (bottom) and a blow up of the resistance data in the same field range (top). Measurements reveal two distinct jumps in resistance, one corresponding to the giant magnetoresistance and the other due to a ferromagnetic transition.

Mentions: We first discuss the spin-dependent electronic transport properties of the device. An electrical current was injected on the device through the ferromagnetic electrodes while an external magnetic field was applied to the system to drive the configuration of the electrodes. We have measured the electrical resistance of the device while gradually varying the strength of the magnetic field. Figure 3(a) shows the result of such a measurement.


Tunable room-temperature ferromagnet using an iron-oxide and graphene oxide nanocomposite.

Lin AL, Rodrigues JN, Su C, Milletari M, Loh KP, Wu T, Chen W, Neto AH, Adam S, Wee AT - Sci Rep (2015)

Device’s electrical properties.(a) Device’s electrical resistance in terms of the Bext. (b) Ferromagnetic pinned electrodes response to an external magnetic field (bottom) and a blow up of the resistance data in the same field range (top). Measurements reveal two distinct jumps in resistance, one corresponding to the giant magnetoresistance and the other due to a ferromagnetic transition.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4477240&req=5

f3: Device’s electrical properties.(a) Device’s electrical resistance in terms of the Bext. (b) Ferromagnetic pinned electrodes response to an external magnetic field (bottom) and a blow up of the resistance data in the same field range (top). Measurements reveal two distinct jumps in resistance, one corresponding to the giant magnetoresistance and the other due to a ferromagnetic transition.
Mentions: We first discuss the spin-dependent electronic transport properties of the device. An electrical current was injected on the device through the ferromagnetic electrodes while an external magnetic field was applied to the system to drive the configuration of the electrodes. We have measured the electrical resistance of the device while gradually varying the strength of the magnetic field. Figure 3(a) shows the result of such a measurement.

Bottom Line: Magnetic materials have found wide application ranging from electronics and memories to medicine.Not only can we tune its transition temperature in a wide range of temperatures around room temperature, but the magnetization can also be tuned from zero to 0.011 A m(2)/kg through an initialization process with two readily accessible knobs (magnetic field and electric current), after which the system retains its magnetic properties semi-permanently until the next initialization process.We construct a theoretical model to illustrate that this tunability originates from an indirect exchange interaction mediated by spin-imbalanced electrons inside the nanocomposite.

View Article: PubMed Central - PubMed

Affiliation: 1] NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore,28 Medical Drive, Singapore 117456 [2] Centre for Advanced 2D Materials and Graphene Research Centre, Faculty of Science, National University of Singapore, 6 Science Drive 2, Singapore 117546 [3] Department of Physics, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore 117542.

ABSTRACT
Magnetic materials have found wide application ranging from electronics and memories to medicine. Essential to these advances is the control of the magnetic order. To date, most room-temperature applications have a fixed magnetic moment whose orientation is manipulated for functionality. Here we demonstrate an iron-oxide and graphene oxide nanocomposite based device that acts as a tunable ferromagnet at room temperature. Not only can we tune its transition temperature in a wide range of temperatures around room temperature, but the magnetization can also be tuned from zero to 0.011 A m(2)/kg through an initialization process with two readily accessible knobs (magnetic field and electric current), after which the system retains its magnetic properties semi-permanently until the next initialization process. We construct a theoretical model to illustrate that this tunability originates from an indirect exchange interaction mediated by spin-imbalanced electrons inside the nanocomposite.

No MeSH data available.