Spin wave device and logic circuit using spin wave device
As a technique for attaining a reduction in power consumption, there is a technique for reducing power consumption using a spin wave. No specific proposal concerning spin wave generation, spin wave detection, and a latch technique for information has been made. A device applies an electric field to a first electrode of a nonmagnetic material using a thin line-shaped stacked body including a first ferromagnetic layer and a nonmagnetic layer to thereby generate a spin wave in the first ferromagnetic layer, and detects a phase or amplitude of the spin wave propagated in the first ferromagnetic layer using a second electrode of a ferromagnetic material with a magnetoresistance effect.
1. A spin wave device comprising:
a thin line-shaped stacked body including a first ferromagnetic layer and a nonmagnetic layer formed on the first ferromagnetic layer;
a first electrode of a nonmagnetic material formed in a first region on the first nonmagnetic layer;
electric-field applying means for applying an electric field to the first electrode to thereby generate a spin wave in the first ferromagnetic layer; and
a second electrode of a ferromagnetic material for detecting, with a magnetoresistance effect, a phase or amplitude of the spin wave propagated in the first ferromagnetic layer, the second electrode being formed in a second region on the first nonmagnetic layer.
2. The spin wave device according to claim 1 , further comprising a circuit that generates a clock signal, wherein
a frequency of the spin wave synchronizes with a frequency of the clock signal, and
timing for applying the electric field to the first electrode and timing for performing the detection by the magnetoresistance effect synchronize with the clock signal.
3. The spin wave device according to claim 1 , wherein
the first electrode is electrically connected to a source electrode of a first selection transistor,
the second electrode is electrically connected to a source electrode of a second selection transistor,
a drain electrode of the first selection transistor is electrically connected to a first bit line,
a gate electrode of the first selection transistor is electrically connected to a first word line,
a drain electrode of the second selection transistor is electrically connected to a second bit line,
a gate electrode of the second selection transistor is electrically connected to a second word line,
both ends of the first ferromagnetic layer are respectively connected to source lines, and
the spin wave device applies a voltage to the first bit line and the first word line, turns on the first selection transistor to excite the spin wave, applies a voltage to the second bit line and the second word line, and turns on the second selection transistor to read resistance in the second region.
4. The spin wave device according to claim 1 , wherein
the first electrode is electrically connected to a first bit line,
the second electrode is electrically connected to a second bit line,
the first ferromagnetic layer in the first region is electrically connected to a drain electrode of a first selection transistor,
the first ferromagnetic layer in the second region is electrically connected to a drain electrode of a second selection transistor,
a source electrode of the first selection transistor and a source electrode of the second selection transistor are respectively electrically connected to source lines,
a gate electrode of the first selection transistor is electrically connected to a first word line,
a gate electrode of the second selection transistor is electrically connected to a second word line, and
the spin wave device applies a voltage to the first bit line and the first word line, turns on the first selection transistor to excite the spin wave, applies a voltage to the second bit line and the second word line, and turns on the second selection transistor to read resistance in the second region.
5. The spin wave device according to claim 1 , further comprising magnetic-field applying means for controlling a propagation direction of the spin wave.
6. The spin wave device according to claim 1 , wherein
the first ferromagnetic layer and the second electrode are made of a ferromagnetic material containing at least one or more kinds of 3d transfer metal, and
the first nonmagnetic layer is made of a material containing oxygen.
7. The spin wave device according to claim wherein
timing of the electric field applied to the first electrode is different such that the phase of the spin wave is different by approximately π/2 according to an input signal of “ 0 ” or “ 1 ”, and
in the second electrode, the difference in the phase of the spin wave is detected by the magnetoresistance effect.
8. The spin wave device according to claim 1 , wherein
timing of the electric field applied to the first electrode is different such that the phase of the spin wave is different by approximately π according to an input signal of “ 0 ” or “ 1 ”, and
in the second electrode, the difference in the phase of the spin wave is detected by the magnetoresistance effect.
9. The spin wave device according to claim 1 , wherein
a magnetic domain wall is introduced into the first ferromagnetic layer,
the magnetic domain wall moves with the spin wave in a different amplitude direction according to an input signal of “ 0 ” or “ 1 ”, and
in the second electrode, the difference in the amplitude direction of the spin wave is detected by the magnetoresistance effect.
10. The spin wave device according to claim 9 , wherein relative positions of the second electrode and the magnetic domain wall can be detected by the magnetoresistance effect even after the spin wave is attenuated.
11. The spin wave device according to claim 9 , wherein
the first ferromagnetic layer includes two magnetization fixing layers, and
the two magnetization fixing layers are a ferromagnetic material having magnetic anisotropy larger than the magnetic anisotropy of the first ferromagnetic layer.
12. The spin wave device according to claim 9 , wherein
the first ferromagnetic layer includes two magnetization fixing layers, and
the two magnetization fixing layers are an antiferromagnetic material.
13. The spin wave device according to claim 1 , wherein
by controlling amplitude of an electric field applied to the second electrode,
a magnetization direction of a part of the first ferromagnetic layer in the second region is locally fixed, and
the spin wave is controlled not to propagate in the first ferromagnetic layer from the first electrode passing over the second electrode.
14. A logic circuit using a spin wave device, comprising:
first and second thin line-shaped stacked bodies including first ferromagnetic layers and nonmagnetic layers formed on the first ferromagnetic layers, the first and second stacked bodies merging in an interference portion;
a first electrode of a nonmagnetic material formed in a first region on the first nonmagnetic layer of the first stacked body;
a second electrode of the nonmagnetic material formed in a second region on the first nonmagnetic layer of the second stacked body;
a third electrode of a ferromagnetic material formed in a third region on the first nonmagnetic layer of the merged stacked body; and
electric-field applying means for applying an electric field to the first and second electrodes to thereby generate different spin waves in the first ferromagnetic layer according to input signals, wherein
when the spin waves interfere in the interference portion, the logic circuit applies an arithmetic operation to the two spin waves induced from the first electrode and the second electrode, and
the logic circuit detects, with a magnetoresistance effect, a phase or amplitude of a propagated spin wave, which is an arithmetic operation result, in the third electrode.
15. The logic circuit using the spin wave device according to claim 14 , wherein
the logic circuit is connected in multiple stages, and
the logic circuit applies an arithmetic operation by spin wave interference to a plurality of input signals.