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Separating read and write units in multiferroic devices.

Roy K - Sci Rep (2015)

Bottom Line: Strain-mediated multiferroic composites, i.e., piezoelectric-magnetostrictive heterostructures, hold profound promise for energy-efficient computing in beyond Moore's law era.This is an important issue since we need to achieve a high magnetoresistance for technological applications.We show here that magnetically coupling the magnetostrictive nanomagnet and the free layer e.g., utilizing the magnetic dipole coupling between them can circumvent this issue.

View Article: PubMed Central - PubMed

Affiliation: School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA.

ABSTRACT
Strain-mediated multiferroic composites, i.e., piezoelectric-magnetostrictive heterostructures, hold profound promise for energy-efficient computing in beyond Moore's law era. While reading a bit of information stored in the magnetostrictive nanomagnets using a magnetic tunnel junction (MTJ), a material selection issue crops up since magnetostrictive materials in general cannot be utilized as the free layer of the MTJ. This is an important issue since we need to achieve a high magnetoresistance for technological applications. We show here that magnetically coupling the magnetostrictive nanomagnet and the free layer e.g., utilizing the magnetic dipole coupling between them can circumvent this issue. By solving stochastic Landau-Lifshitz-Gilbert equation of magnetization dynamics in the presence of room-temperature thermal fluctuations, we show that such design can eventually lead to a superior energy-delay product.

No MeSH data available.


Related in: MedlinePlus

An illustrative distribution of switching delay for the case of magnetostrictive nanomagnet.A moderately large number (10,000) of simulations have been performed in the presence of room-temperature (300 K) thermal fluctuations. The dipole-coupled free layer is considered in this case and 30 MPa stress is applied with 60 ps ramp (rise and fall) time. This wide distribution is caused by the following two reasons: (1) thermal fluctuations make the initial orientation of magnetization a distribution, and (2) thermal kicks during the switching makes the switching delay a distribution too; the former one has a higher effect than that of the latter. The mean and standard deviation of this distribution are 0.379 ns and 0.080 ns, respectively.
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f3: An illustrative distribution of switching delay for the case of magnetostrictive nanomagnet.A moderately large number (10,000) of simulations have been performed in the presence of room-temperature (300 K) thermal fluctuations. The dipole-coupled free layer is considered in this case and 30 MPa stress is applied with 60 ps ramp (rise and fall) time. This wide distribution is caused by the following two reasons: (1) thermal fluctuations make the initial orientation of magnetization a distribution, and (2) thermal kicks during the switching makes the switching delay a distribution too; the former one has a higher effect than that of the latter. The mean and standard deviation of this distribution are 0.379 ns and 0.080 ns, respectively.

Mentions: To investigate the performance metrics with the incorporation of the dipole-coupled free layer further, we increase the stress to 30 MPa and tabulate the results as case (c) in the Table 1. We note that the mean switching delay has got reduced compared to the case (a) while they incur the same amount of energy dissipation due to Gilbert damping. We plot the corresponding switching delay distribution for the case (c) in the Fig. 3. Such distribution can be achieved experimentally by time-resolved measurements54. It needs to be pointed out that we can generate a maximum amount of stress on the magnetostrictive layer dictated by the maximum strain induced in it, so we also consider 30 MPa stress without the free layer and tabulate the results as case (d). The mean switching delay for case (d) is very close to that of case (c), but it has the highest energy dissipation Etotal (and also ) among the four cases considered, while case (c) has the lowest . Assuming a performance metric , where  =  + 10, the case (c) still would have the lower product compared to the case (d).


Separating read and write units in multiferroic devices.

Roy K - Sci Rep (2015)

An illustrative distribution of switching delay for the case of magnetostrictive nanomagnet.A moderately large number (10,000) of simulations have been performed in the presence of room-temperature (300 K) thermal fluctuations. The dipole-coupled free layer is considered in this case and 30 MPa stress is applied with 60 ps ramp (rise and fall) time. This wide distribution is caused by the following two reasons: (1) thermal fluctuations make the initial orientation of magnetization a distribution, and (2) thermal kicks during the switching makes the switching delay a distribution too; the former one has a higher effect than that of the latter. The mean and standard deviation of this distribution are 0.379 ns and 0.080 ns, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4471893&req=5

f3: An illustrative distribution of switching delay for the case of magnetostrictive nanomagnet.A moderately large number (10,000) of simulations have been performed in the presence of room-temperature (300 K) thermal fluctuations. The dipole-coupled free layer is considered in this case and 30 MPa stress is applied with 60 ps ramp (rise and fall) time. This wide distribution is caused by the following two reasons: (1) thermal fluctuations make the initial orientation of magnetization a distribution, and (2) thermal kicks during the switching makes the switching delay a distribution too; the former one has a higher effect than that of the latter. The mean and standard deviation of this distribution are 0.379 ns and 0.080 ns, respectively.
Mentions: To investigate the performance metrics with the incorporation of the dipole-coupled free layer further, we increase the stress to 30 MPa and tabulate the results as case (c) in the Table 1. We note that the mean switching delay has got reduced compared to the case (a) while they incur the same amount of energy dissipation due to Gilbert damping. We plot the corresponding switching delay distribution for the case (c) in the Fig. 3. Such distribution can be achieved experimentally by time-resolved measurements54. It needs to be pointed out that we can generate a maximum amount of stress on the magnetostrictive layer dictated by the maximum strain induced in it, so we also consider 30 MPa stress without the free layer and tabulate the results as case (d). The mean switching delay for case (d) is very close to that of case (c), but it has the highest energy dissipation Etotal (and also ) among the four cases considered, while case (c) has the lowest . Assuming a performance metric , where  =  + 10, the case (c) still would have the lower product compared to the case (d).

Bottom Line: Strain-mediated multiferroic composites, i.e., piezoelectric-magnetostrictive heterostructures, hold profound promise for energy-efficient computing in beyond Moore's law era.This is an important issue since we need to achieve a high magnetoresistance for technological applications.We show here that magnetically coupling the magnetostrictive nanomagnet and the free layer e.g., utilizing the magnetic dipole coupling between them can circumvent this issue.

View Article: PubMed Central - PubMed

Affiliation: School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA.

ABSTRACT
Strain-mediated multiferroic composites, i.e., piezoelectric-magnetostrictive heterostructures, hold profound promise for energy-efficient computing in beyond Moore's law era. While reading a bit of information stored in the magnetostrictive nanomagnets using a magnetic tunnel junction (MTJ), a material selection issue crops up since magnetostrictive materials in general cannot be utilized as the free layer of the MTJ. This is an important issue since we need to achieve a high magnetoresistance for technological applications. We show here that magnetically coupling the magnetostrictive nanomagnet and the free layer e.g., utilizing the magnetic dipole coupling between them can circumvent this issue. By solving stochastic Landau-Lifshitz-Gilbert equation of magnetization dynamics in the presence of room-temperature thermal fluctuations, we show that such design can eventually lead to a superior energy-delay product.

No MeSH data available.


Related in: MedlinePlus