Magnetic memory and information recording and reproducing method therefor

A magnetic memory comprising:

• a variable resistor including a first magnetic layer for storing information on a basis of a direction of magnetization, a non-magnetic layer, and a second magnetic layer having a coercive force that is smaller than a coercive force of the first magnetic layer, the variable resistor exhibiting different resistances according to magnetization directions of the first magnetic layer and the second magnetic layer;
• a magnetic field generating means for initializing magnetization of the second magnetic layer and reversing the initialized magnetization;
• a circuit for detecting a resistance value of the variable resistor;
• a storage circuit of holding the detected resistance value;
• and
• a signal detecting circuit for outputting a reproduction signal by comparing the held resistance value with a resistance value of the variable resistor obtained after the magnetization of the second magnetic layer is reversed from a magnetization state corresponding to the held resistance value.

A nonvolatile solid-state magnetic memory comprising:

• a magneto-resistance element having a first magnetic layer, a second magnetic layer whose coercive force is smaller than a coercive force of the first magnetic layer, and a non-magnetic layer sandwiched between the first magnetic layer and the second magnetic layer, the magneto-resistance element exhibiting different resistances according to magnetization directions of the first magnetic layer and the second magnetic layer;
• a bit line connected to one end of the magneto-resistance element;
• a sense amplifier that compares a first potential and a second potential, the first potential being generated in the bit line if the first magnetic layer and the second magnetic layer are magnetized parallel to each other in the same direction, the second potential being generated in the bit line if the first magnetic layer and the second magnetic layer are magnetized parallel to each other in an opposite direction;
• and
• a noise eliminating means for eliminating noise generated in the bit line when the magnetization direction of the second magnetic layer is reversed.

An information reproducing method for a nonvolatile solid-state magnetic memory including a first magnetic layer, a second magnetic layer whose coercive force is smaller than a coercive force of the first magnetic layer, and a magneto-resistance element in which 1-bit information is stored according to magnetization directions of the first magnetic layer and the second magnetic layer, the maganeto-resistance element being connected to a line that is supplied with a predetermined current,

• the information reproducing method comprising the steps of:
• reading the information stored in the magneto-resistance element by comparing a first potential and a second potential, the first potential being generated in the bit line if the first magnetic layer and the second magnetic layer are magnetized parallel to each other in the same direction, the second potential being generated in the bit line if the first magnetic layer and the second magnetic layer are magnetized parallel to each other in an opposite direction;
• and
• electrically floating the bit line when the magnetization direction of the second magnetization layer is reversed.

An information reproducing method for a nonvolatile solid-state magnetic memory including a first magnetic layer, a second magnetic layer whose coercive force is smaller than a coercive force of the first magnetic layer, a non-magnetic layer sandwiched between the first magnetic layer and the second magnetic layer, and a magneto-resistance element that exhibits different resistances according to magnetization directions of the first magnetic layer and the second magnetic layer, the magneto-resistance element being connected to a bit line,

• the information reproducing method comprising the steps of:
• reading information stored in the magneto-resistance element by comparing a first potential and a second potential, the first potential being generated in the bit line if the first magnetic layer and the second magnetic layer are magnetized parallel to each other in the same direction, the second potential being generated in the bit line if the first magnetic layer and the second magnetic layer are magnetized parallel to each other in an opposite direction;
• and
• grounding the bit line at predetermined impedance when the magnetization direction of the second magnetic layer is reversed.

A portable information processing apparatus comprising:

• a magnetic memory comprising:
• a variable resistor including a first magnetic layer for storing information on a basis of a direction of magnetization, a non-magnetic layer, and a second magnetic layer having a coercive force that is smaller than a coercive force of the first magnetic layer, the variable resistor exhibiting different resistances according to magnetization directions of the first magnetic layer and the second magnetic layer;
• a magnetic field generating means for initializing magnetization of the second magnetic layer and reversing the initialized magnetization;
• a circuit for detecting a resistance value of the variable resistor;
• a storage circuit of holding the detected resistance value;
• and
• a signal detecting circuit for outputting a reproduction signal by comparing the held resistance value with a resistance value of the variable resistor obtained after the magnetization of the second magnetic layer is reversed from a magnetization state corresponding to the held resistance value;
• and
• a control means that operates according to a program stored in the memory.

An information recording and reproducing method for a nonvoltaic memory including a variable resistor for storing information, the variable resistor exhibiting at least two different resistance values, the information recording and reproducing method comprising the steps of:

• initializing a resistance of the variable resistor in a first state;
• detecting a resistance value of the first state of the variable resistor and holding the detected resistance value as a first resistance value;
• detecting a second resistance value by changing from the first state to a second state of the variable resistor and comparing the first resistance value with the second resistance value;
• and
• reproducing information according to a result of the comparison.

A nonvoltaic memory comprising:

• a variable resistor for storing information on a basis of a resistance value, the variable resistor exhibiting at least two different resistance values;
• a recording means for initializing a resistance of the variable resistor to a first resistance value and changing from the first resistance value to a second resistance value;
• a circuit for detecting a resistance value of the variable resistor;
• a storage circuit of holding the detected resistance value;
• and
• a signal detecting circuit for outputting a reproduction signal by comparing the first resistance value with the second resistance value.

An information reproducing method for a nonvoltaic solid-state memory including a variable resistor exhibiting at least two different resistance values, the information reproducing method comprising:

• reading first resistance and second resistance values of the variable resistor;
• comparing the first and second resistance values of the variable resistor;
• and
• electrically floating the bit line when the resistance value of the variable resistor is changed.