Thursday 28 August 2014

Goethite NPs

Magnetic properties of ultra-small goethite nanoparticles.

E Brok, C Frandsen, D E Madsen, H Jacobsen, J O Birk, K Lefmann, J Bendix, K S Pedersen, C B Boothroyd, A A Berhe,G G Simeoni and S Mørup
J. Phys. D 47, 365003 (2014)
ZFC/FC magnetization curves for the sample GBM obtained in an applied field of (top) 4.8 T and (bottom) 2.0 mT. The magnetization is given per kg of goethite in the sample.


Spin transfer torques in AF

Spin Pumping and Spin-Transfer Torques in Antiferromagnets.
Ran Cheng, Jiang Xiao, Qian Niu, and Arne Brataas
Phys. Rev. Lett. 113, 057601 (2014)
The two eigenmodes of Eq. (2) have opposite chiralities and opposite ratios between the cone angles of m1 and m2. A magnetic field along the easy axis breaks the degeneracy of the two modes.

Thermal stability of skyrmion lattice

Thermal Stability of an Interface-Stabilized Skyrmion Lattice.

A. Sonntag, J. Hermenau, S. Krause, and R. Wiesendanger

Phys. Rev. Lett. 113, 077202 (2014)
(a)–(c) SP-STM data of Fe/Ir(111) at different temperatures. For all images the same color scale and tunneling parameters were used (25×25nm2, U=10  mV I=4  nA). The insets show the corresponding Fourier transforms. Black circles mark the contribution from the magnetic unit cell and gray circles the spots caused by the TAMR effect. (d) Line profiles along the direction indicated in (a)–(c).

Tuesday 26 August 2014

Coupled Skyrmions

Flower-like dynamics of coupled Skyrmions with dual resonant modes by a single-frequency microwave magnetic field.
Yingying Dai, Han Wang, Teng Yang, Weijun Ren & Zhidong Zhang
Scientific Reports 4, 6153 (2014)
Sketch of the topological density distribution and two excitation modes of skyrmion dynamics.

Three dimensional magnetic abacus memory

Three dimensional magnetic abacus memory.
ShiLei Zhang, JingYan Zhang, Alexander A. Baker, ShouGuo Wang, GuangHua Yu, Thorsten Hesjedal
Scientific Reports 4, 6109 (2014)
(a) Generic concept for magnetic 3D memory. Typically several magnetic units are stacked on top of each other, where each unit stores one bit of information. In a conventional scheme, the magnetisation state of a unit depends on the sequence of bits in the stack, i.e., |1000〉, …, |0001〉 going from left to right in the example shown. However, if the layers are treated as indistinguishable, the state of the stack is adequately described by only counting the number of spin-up layers. In this way, all four states shown in (a) have the same logic value of ‘1’. (b–f) illustrate the five logic states a four-layer stack can store: |0〉, |1〉, |2〉, |3〉, and |4〉, respectively. This counting scheme is analogous to the beads in an abacus, as shown for comparison.