# US 9,753,102 B1 · Silicon-based magnetometer

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- Number: US 9,753,102 B1
- Document ID: US9753102B1
- Status: Granted
- Kind: B1
- Application number: 14/190,656
- Filed: 2014-02-26
- Granted: 2017-09-05
- Earliest claimed: 2013-02-28
- Assignees: University of South Florida
- Applicants: University of South Florida
- Inventors: Denis Karaiskaj
- Web page: https://patentgrep.com/patent/US9753102B1

## CPC

- G01R 33/24: for measuring direction or magnitude of magnetic fields or magnetic flux
- G01R 33/26: using optical pumping
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

Systems and methods for a magnetometer comprise a single-isotope silicon crystal doped with impurity atoms. The Larmor precession associated with energy level transitions of the impurity atoms may be detected and used to measure an external magnetic field.

## Claims

### Claim 1

A magnetometer, comprising:
a single-isotope silicon crystal doped with impurity atoms, wherein a Larmor precession associated with energy level transitions of the impurity atoms is detected and used to measure an external magnetic field, and wherein the Larmor precession is detected electrically based at least in part on a photoconductivity measurement of the single-isotope silicon crystal.

### Claim 2 (depends on 1)

The magnetometer of claim 1, wherein the single-isotope silicon crystal is a 28Si crystal.

### Claim 3 (depends on 1)

The magnetometer of claim 1, wherein the impurity atoms are single-isotope impurity atoms.

### Claim 4 (depends on 1)

The magnetometer of claim 1, wherein the impurity atoms are selected from the group consisting of phosphorus (P), arsenic (As), antimony (Sb), lithium (Li), sodium (Na), sulfur (S), selenium (Se), tellurium (Te), boron (B), gallium (Ga), indium (In), aluminum (Al), beryllium (Be), zinc (Zn), gold (Au), silver (Ag), platinum (Pt), bismuth (Bi), and copper (Cu) atoms, and combinations thereof.

### Claim 5 (depends on 1)

The magnetometer of claim 1, wherein the energy level transitions originate from neutral donors or acceptors of the impurity atoms.

### Claim 6 (depends on 1)

The magnetometer of claim 1, further comprising a light source adapted to excite the impurity atoms within the silicon crystal.

### Claim 7 (depends on 6)

The magnetometer of claim 6, further comprising an apparatus configured to interrogate hyperfine splitting resulting from an interaction of impurity nuclei and donor electrons.

### Claim 8 (depends on 1)

The magnetometer of claim 1, further comprising at least two capacitor plates positioned at opposite ends of the single-isotope silicon crystal, the at least two capacitor plates adapted to measure photoconductivity.

### Claim 9 (depends on 1)

The magnetometer of claim 1, wherein the magnetometer is operable at room temperature.

### Claim 10

A method for measuring a magnetic field, the method comprising
applying light from one or more light sources onto a single-isotope silicon crystal to excite impurity atoms of the single-isotope silicon crystal;
detecting a Larmor precession associated with the impurity atoms of the single-isotope silicon crystal based at least in part on energy level transitions of the impurity atoms; and
calculating a magnetic field measurement based at least in part on the Larmor precession,
wherein detecting the Larmor precession comprises detecting changes in photoconductivity of the single-isotope silicon crystal.

### Claim 11 (depends on 10)

The method of claim 10, wherein the single-isotope silicon crystal is a 28Si crystal.

### Claim 12 (depends on 10)

The method of claim 10, wherein the impurity atoms are single-isotope impurity atoms.

### Claim 13 (depends on 10)

The method of claim 10, wherein the impurity atoms are selected from the group consisting of phosphorus (P), arsenic (As), antimony (Sb), lithium (Li), sodium (Na), sulfur (S), selenium (Se), tellurium (Te), boron (B), gallium (Ga), indium (In), aluminum (Al), beryllium (Be), zinc (Zn), gold (Au), silver (Ag), platinum (Pt), bismuth (Bi), and copper (Cu) atoms, and combinations thereof.

### Claim 14 (depends on 10)

The method of claim 10, wherein detecting the Larmor precession comprises detecting resonance of hyperfine splitting levels resulting from the energy level transitions originating from neutral donors or acceptors of the impurity atoms.

### Claim 15 (depends on 10)

The method of claim 10, further comprising applying a nuclear magnetic resonance to the single-isotope silicon crystal to interrogate hyperfine splitting resulting from an interaction of impurity nuclei and donor electrons.

### Claim 16 (depends on 10)

The method of claim 10, further comprising applying a pump laser and a probe laser to the single-isotope silicon crystal to optically detect the Larmor precession.

### Claim 17

A magnetometer, comprising:
a single-isotope silicon crystal doped with impurity atoms, wherein a Larmor precession associated with energy level transitions of the impurity atoms is detected and used to measure an external magnetic field, and wherein the Larmor precession is detected optically.

### Claim 18 (depends on 17)

The magnetometer of claim 17, further comprising a pump laser and a probe laser for optically detecting the Larmor precession, wherein the pump laser projects light onto the single-isotope silicon crystal in the z-direction and the probe laser projects light onto the single-isotope silicon crystal in the x-direction.

### Claim 19 (depends on 17)

The magnetometer of claim 17, wherein the single-isotope silicon crystal is a 28Si crystal.

### Claim 20 (depends on 17)

The magnetometer of claim 17, wherein the magnetometer is operable at room temperature.