The switching speed of a granular perpendicular recording medium is investigated using finite-element micromagnetic calculations. The switching behavior sensitively depends on the intergrain exchange coupling, the grain-size distribution, and the degree of alignment of easy axes. These effects are investigated using subgrain discretization. In irregular microstructures the switching time decreases considerably with decreasing intergrain exchange.

Perpendicular recording

Micromagnetics

Switching time

Degree (music)

10.1109/tmag.2003.816277

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Citations (1)

Finite element simulation of discrete media with granular structure

IEEE Transactions on Magnetics (2002)

R. Dittrich T. Schrefl H. Förster Dieter Suess W. Scholz

Discrete media show great potential for future ultra-high density magnetic recording. A hybrid finite element/boundary element method is used to compare the magnetization reversal process in a perpendicular granular film, patterned media, and a single magnetic island. The results show that the influence of magnetostatic interactions on the switching field is comparable with the spread of the nucleation field due to the dispersion of the magnetic easy axes. For CoCrPt, this value is about 75 kA/m.

Patterned media

Magnetostatics

10.1109/tmag.2002.802786

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Citations (10)

Thermally induced magnetization reversal in antiferromagnetically coupled media

Journal of Applied Physics (2003)

R. Dittrich T. Schrefl Dieter Suess W. Scholz H. Förster

The calculation of energy barriers between stable equilibrium states in strongly interacting systems requires the calculation of saddle points in high dimensional energy landscapes. We combine the nudged elastic band method with finite element micromagnetics to calculate optimal paths, giving a global view of thermal switching in antiferromagnetically coupled media. Energy barriers and transition rates can be estimated from the saddle points and the energy minima along this path. We investigate the dependence of the energy barrier on the strength of the antiferromagnetic coupling and study the reversal in the data bit transition region. Below 1.1 mJ/m2 a two step reversal occurs passing a metastable state. Above 1.1 mJ/m2 this metastable state disappears and the energy barrier is constant for a coupling strength greater than 1.5 mJ/m2.

Micromagnetics

Metastability

Saddle point

Maxima and minima

Saddle

Energy landscape

10.1063/1.1558237

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Citations (4)

Thermal Select MRAM with a 2-bit Cell Capability for beyond 65 nm Technology Node

International Electron Devices Meeting (2006)

Rainer Leuschner Ulrich Klostermann H. Park F. Dahmani R. Dittrich

We report on a novel thermal select (TS) MRAM with multilevel programming capability. Exchange bias pinning of a magnetic free layer (FL) was used to achieve a thermally stable bit and to reduce writing currents. This report shows experimental data for a TS-based magnetic tunnel junction (MTJ) with a size of 50 times90 nm ² , the smallest size reported so far. Multilevel capability with 2 bits per 1-transistor and 1-MTJ (1T1MTJ) is also demonstrated on a 70 times 140 nm ² MTJ. With the advanced 2-bit cell concept, a 70% increase in effective bit density can be achieved at 65 nm technology node

Magnetoresistive random-access memory

Tunnel magnetoresistance

Cell size

10.1109/iedm.2006.346986

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Citations (9)

MICROMAGNETIC SIMULATIONS AND APPLICATIONS

T. Schrefl Dieter Suess H. ROSTER V. Tsiantos W. Scholz

Micromagnetics

10.1142/9789812777140_0011

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Citations (2)

Computational Aspects of Micromagnetics

Elsevier eBooks (2006)

R. Dittrich T. Schrefl J. Fidler Dieter Suess W. Scholz

Micromagnetics

10.1016/b978-012480874-4/50016-6

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Citations (0)

Magnetostatic spin waves in nanoelements

Physica B Condensed Matter (2003)

J. Fidler T. Schrefl W. Scholz Dieter Suess V. Tsiantos

Micromagnetics

Magnetization dynamics

Oscillation (cell signaling)

Landau–Lifshitz–Gilbert equation

Spin wave

Square (algebra)

Domain wall (magnetism)

10.1016/j.physb.2003.08.094

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Citations (16)

Energy barriers in magnetic random access memory elements

Digest of INTERMAG 2003. International Magnetics Conference (Cat. No.03CH37401) (2004)

R. Dittrich T. Schrefl H. Förster Dieter Suess W. Scholz

In this paper, energy barriers in magnetic random access memory elements were calculated. Three minimum energy paths for the thermal reversal of a thin NiFeCo MRAM element were found between the two stable states.

Magnetoresistive random-access memory

Random access

10.1109/intmag.2003.1230563

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Citations (1)

Migrating from planar to FinFET for further CMOS scaling: SOI or bulk?

Proceedings of ESSCIRC (2009)

T. Chiarella Liesbeth Witters A. Mercha C. Kerner R. Dittrich

The multi-gate architecture is considered as a key enabler for further CMOS scaling. FinFETs can readily be manufactured on SOI or bulk substrates. We report for the first time an extensive benchmark of their critical electrical figures of merit. Both alternatives show better scalability than PLANAR CMOS and exhibit similar intrinsic device performance. Introducing SOI substrates and low doped fins results in lower junction capacitance, higher mobility and voltage gain with reduced mismatch. Using an optimized integration to minimize parasitics we demonstrate high-performing FinFET ring-oscillators with delays down to 10 ps/stage for both SOI and bulk FinFETs and working SRAM cells at VDD = 1.0 V.

Parasitic extraction

Benchmark (surveying)

10.1109/esscirc.2009.5325993

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Citations (27)