Multilevel antiferromagnetic memory device

A memory device comprising:

• a plurality of first word lines extending in a first direction;
• a plurality of bit lines above the first word lines and extending in a second direction crossing the first direction;
• a plurality of second word lines above the bit lines and extending in the first direction;
• a plurality of lower memory cells, each of which is located between one of the first word lines and one of the bit lines;
• and
• a plurality of upper memory cells, each of which is located between one of the bit lines and one of the second word lines,
• each of the lower memory cells including a first variable resistance element, a first ferromagnetic layer, a first insulating layer, a second ferromagnetic layer, a non-magnetic first metal layer, and a third ferromagnetic layer stacked in order in a third direction crossing the first and second directions such that the first variable resistance element is in contact with an upper surface of said one of the first word lines and said one of the bit lines is in contact with an upper surface of the third ferromagnetic layer, wherein the second ferromagnetic layer and the third ferromagnetic layer have magnetizations in opposite directions, and
• each of the upper memory cells including a second variable resistance element, a fourth ferromagnetic layer, a second insulating layer, a fifth ferromagnetic layer, a non-magnetic second metal layer, and a sixth ferromagnetic layer stacked in order in the third direction such that the second variable resistance element is in contact with an upper surface of said one of the bit lines and said one of the second word lines is in contact with an upper surface of the sixth ferromagnetic layer, wherein the fifth ferromagnetic layer and the sixth ferromagnetic layer have magnetizations in opposite directions,
• wherein each of the lower memory cells goes into a low resistance state in response to a current having at least a first magnitude flowing therethrough in a direction from the first word lines to the bit lines, and each of the upper memory cells goes into a low resistance state in response to a current of at least a second magnitude, which is larger than the first magnitude, flowing therethrough in a direction from the bit lines to the second word lines, and
• wherein each of the lower memory cells goes into a high resistance state in response to a current having at least a third magnitude flowing therethrough in a direction from the bit lines to the first word lines, and each of the upper memory cells goes into a high resistance state in response to a current of at least a fourth magnitude, which is smaller than the third magnitude, flowing therethrough in a direction from the second word lines to the bit lines.

A memory device comprising:

• a first conductor;
• a first stacked body above the first conductor, the first stacked body including a first variable resistance element, a first ferromagnetic layer above the first variable resistance element, a first insulating layer above the first ferromagnetic layer, a second ferromagnetic layer above the first insulating layer, a non-magnetic first metal layer above the second ferromagnetic layer, and a third ferromagnetic layer above the non-magnetic first metal layer, wherein the second ferromagnetic layer and the third ferromagnetic layer have magnetizations in opposite directions;
• a second conductor above the first stacked body;
• a second stacked body above the second conductor, the second stacked body including a second variable resistance element, a fourth ferromagnetic layer above the second variable resistance element, a second insulating layer above the fourth ferromagnetic layer, a fifth ferromagnetic layer above the second insulating layer, a non-magnetic second metal layer above the fifth ferromagnetic layer, and a sixth ferromagnetic layer above the non-magnetic second metal layer, wherein the fifth ferromagnetic layer and the sixth ferromagnetic layer have magnetizations in opposite directions, and the sixth ferromagnetic layer has a volume larger than a volume of the third ferromagnetic layer;
• and
• a third conductor above the second stacked body.