Spin transport type magnetic sensor
The magnetic sensor includes a base substrate having a magnetic shield layer; a single-domain semiconductor crystal layer attached via an insulating film on the magnetic shield layer of the base substrate; a first ferromagnetic layer formed on top of the semiconductor crystal layer on the opposite side of the semiconductor crystal layer to the insulating film, via a first tunnel barrier layer; and a second ferromagnetic layer formed, at a distance from the first ferromagnetic layer, on top of the semiconductor crystal layer on the opposite side of the semiconductor crystal layer to the insulating film, via a second tunnel barrier layer.
1. A magnetic sensor comprising:
a base substrate having a magnetic shield layer;
a single-domain semiconductor crystal layer attached via an insulating film on the magnetic shield layer of the base substrate;
a first ferromagnetic layer formed on top of the semiconductor crystal layer on the opposite side of the semiconductor crystal layer to the insulating film, via a first tunnel barrier layer; and
a second ferromagnetic layer formed, at a distance from the first ferromagnetic layer, on top of the semiconductor crystal layer on the opposite side of the semiconductor crystal layer to the insulating film, via a second tunnel barrier layer.
2. The magnetic sensor according to claim 1 comprising:
a first electrode which is provided on the semiconductor crystal layer on the opposite side of the semiconductor crystal layer to the insulating film and allows electrons to flow between the first electrode and the first ferromagnetic layer; and
a second electrode which is provided on the semiconductor crystal layer on the opposite side of the semiconductor crystal layer to the insulating film and used for measuring voltage between the second ferromagnetic layer.
3. The magnetic sensor according to claim 1 , wherein the semiconductor crystal layer is made of Si, Ge, GaAs or graphene.
4. The magnetic sensor according to claim 1 , wherein the semiconductor crystal layer has a protruding part whose tip is located on the side of an air bearing surface of a magnetic head.
5. The magnetic sensor according to claim 4 , further comprising, on the base substrate on the side of the air bearing surface, a magnetic shield having a through-hole in which the protruding part exists, and the through-hole is located on a side face of the semiconductor crystal layer corresponding to a region between the first ferromagnetic layer and the second ferromagnetic layer.
6. The magnetic sensor according to claim 1 , wherein the first and second tunnel barrier layers are made of MgO, Al 2 O 3 , SiO 2 , ZnO or MgAl 2 O 4 .
7. The magnetic sensor according to claim 1 , wherein the first and second tunnel barrier layers are each formed of a Schottky barrier formed at an interface of the semiconductor substrate and a metal layer Schottky-contacting thereto.
8. The magnetic sensor according to claim 1 , wherein the thickness of the semiconductor crystal layer is 0.4 nm or more and 70 nm or less.
9. The magnetic sensor according to claim 1 , wherein magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer are opposite to each other.
10. The magnetic sensor according to claim 2 , wherein magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer are the same.
11. The magnetic sensor according to claim 1 , wherein the semiconductor crystal layer is formed of a semiconductor having a diamond structure or a zincblende structure.