Electromagnetic detection apparatus and methods

A system for use in detecting an electromagnetic wave, comprising:

• a device comprising:
• a first magnetic layer having a fixed magnetization direction;
• a second magnetic layer having an unfixed magnetization direction responsive to the electromagnetic wave;
• and
• a barrier layer positioned between the first and second magnetic layers;
• wherein the device has an impedance dependent on a relative angle between the fixed magnetization direction and the unfixed magnetization direction;
• an external magnetic field source for applying a magnetic field to the device;
• and
• a detector configured to measure a change in the impedance indicative of the electromagnetic wave, wherein exposure of the device to the electromagnetic wave causes the change in impedance of the device,
• wherein the applied magnetic field causes a peak in the change in the impedance of the device, the peak corresponding to the frequency of the electromagnetic wave.

A system for use in detecting an electromagnetic wave, comprising:

• a plurality of devices, each device comprising:
• a first magnetic layer having a fixed magnetization direction;
• a second magnetic layer having an unfixed magnetization direction responsive to the electromagnetic wave;
• and
• a barrier layer positioned between the first and second magnetic layers;
• wherein each device has an impedance dependent on a relative angle between the fixed magnetization direction and the unfixed magnetization direction;
• a receiver for receiving the electromagnetic wave and transmitting the electromagnetic wave to the plurality of devices, the receiver having a plurality of sections corresponding to the plurality of devices;
• the plurality of sections configured such that the electromagnetic wave will have a different power density in each section of the receiver;
• and
• a detector configured to detect a change in the impedance of at least one of the plurality of devices, the change in impedance indicative of the electromagnetic wave.

A system for use in detecting a relative phase of a received electromagnetic wave, comprising:

• a reference electromagnetic wave generator configured to adjust a frequency of the reference electromagnetic wave;
• a device comprising:
• a first magnetic layer having a fixed magnetization direction;
• a second magnetic layer having an unfixed magnetization direction at least partially dependent on the received electromagnetic wave and the reference electromagnetic wave;
• and
• a barrier layer positioned between the first and second magnetic layers;
• wherein the device has an impedance dependent on a relative angle between the fixed magnetization direction and the unfixed magnetization direction;
• and
• a detector configured to detect a change in the voltage across the device indicative of the relative phase of the received electromagnetic wave,
• wherein when the frequency of the reference electromagnetic wave is the same as the frequency of the received electromagnetic wave, the detector measures a phase-dependent voltage across the device.

A method for detecting an electromagnetic wave, comprising the steps of:

• positioning a spintronic device in order to receive the electromagnetic wave, the device having:
• a first magnetic layer having a fixed magnetization direction;
• a second magnetic layer having an unfixed magnetization direction responsive to the electromagnetic wave;
• and
• a barrier layer positioned between the first and second magnetic layers;
• wherein the device has an impedance dependent on a relative angle between the fixed magnetization direction and the unfixed magnetization direction, the relative angle initially configured to be approximately 90 degrees;
• determining a change in the impedance of the device;
• and
• detecting a frequency of the electromagnetic wave based on the change in the impedance of the device by:
• applying an external DC magnetic field to the device;
• sweeping the external DC magnetic field to produce a peak in the change in the impedance of the device;
• and
• detecting the frequency of the electromagnetic wave based on the peak in the change in the impedance of the device.

A method for detecting an electromagnetic wave, comprising the steps of:

• positioning a spintronic device in order to receive the electromagnetic wave, the device having:
• a first magnetic layer having a fixed magnetization direction;
• a second magnetic layer having an unfixed magnetization direction responsive to the electromagnetic wave;
• and
• a barrier layer positioned between the first and second magnetic layers;
• wherein the device has an impedance dependent on a relative angle between the fixed magnetization direction and the unfixed magnetization direction, the relative angle initially configured to be one of approximately 0 degrees and 180 degrees;
• applying an external DC magnetic field to the device;
• sweeping the external DC magnetic field to cause the relative angle to switch from the one of approximately 0 degrees and approximately 180 degrees to the other one of approximately 0 degrees and approximately 180 degrees;
• determining a change in voltage across the device adjacent to a switching region of the relative angle;
• and
• detecting the electromagnetic wave based on the change in the voltage across the device.