Ferromagnetic material

• US 20060148105A1
• Filed: 02/06/2004
• Published: 07/06/2006
• Est. Priority Date: 02/06/2003
• Status: Active Grant

• Current Assignee: Spintronix AB
• Original Assignee: NM Spintronics AB
• Inventors: Sharma, Parmanand, Ahuja, Rajeev, Johansson, Borje, Rao, Kudumboor Venkat
• Granted Patent: US 7,527,983 B2
• Time in Patent Office: Days
• US Class Current: 438/3
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: C04B 2235/3267 MnO2
• CPC Class Codes: C04B 2235/3284 Zinc oxides, zincates, cadmium oxides, cadmiates, mercury oxides, mercurates or oxide forming salts thereof
• CPC Class Codes: C04B 2235/9653 Translucent or transparent ceramics other than alumina
• CPC Class Codes: C04B 35/453 based on zinc, tin, or bismuth oxides or solid solutions thereof with other oxides, e.g. zincates, stannates or bismuthates
• CPC Class Codes: H01F 1/0009 Antiferromagnetic materials, i.e. materials exhibiting a Néel transition temperature H01F1/0036 takes precedence
• CPC Class Codes: H01F 1/0045 Zero dimensional, e.g. nanoparticles, soft nanoparticles for medical/biological use preparation of fullerenes in general C01B32/15
• CPC Class Codes: H01F 1/401 diluted
• CPC Class Codes: H01F 1/402 of II-VI type, e.g. Zn1-x Crx Se
• CPC Class Codes: H01F 10/193 Magnetic semiconductor compounds in general H01F1/40; multilayers, e.g. superlattices H01F10/3213
• CPC Class Codes: H01F 41/0246 Manufacturing of magnetic circuits by moulding or by pressing powder magnetic cores made by moulding or by pressing powder H01F27/255; soft magnetic particles H01F1/20, H01F1/36
• CPC Class Codes: H01F 41/18 by cathode sputtering
• CPC Class Codes: H01F 41/205 by laser ablation, e.g. pulsed laser deposition [PLD]
• CPC Class Codes: H10N 30/853 Ceramic compositions
• CPC Class Codes: H10N 50/85 Magnetic active materials

Abstract

A method is provided for producing a doped dilute ferromagnetic semiconductor material, by doping Zinc Oxide in bulk form with manganese to a maximum level of 5 atomic percent concentration. The material is preferably sintered at a maximum temperature of 650° C. The result of this process is a semiconductor material comprising Mn-doped ZnO with a Mn concentration not exceeding 5 atomic percent, wherein the Mn-doped ZnO is ferromagnetic within at least a part of the temperature range from about 218 Kelvin to about 425 Kelvin.

Claims

1. A. method for producing a ferromagnetic semiconductor material comprising Mn doped ZnO comprising the following steps:

mixing appropriate amounts of ZnO and MnO₂ powders forming a mixture in powder form, and,

sintering said mixture at a maximum temperature of about 700°

C., whereby Mn doped ZnO having a Mn concentration below 5 atomic % and which is ferromagnetic at least at one temperature in the range in temperature from 218 Kelvin to 425 Kelvin is obtained.

5. The method as recited in claim 1 further comprising the step of:

subjecting said mixture to a calcining process, before the step of sintering the mixture.

6. The method as recited in claim 5, wherein said calcining process is carried out at a temperature below 500°

C.

7. The method as recited in claim 1, further comprising the step of:

processing, by means of particle size selection, said Mn doped ZnO having a Mn concentration below 5 atomic % arid which is ferromagnetic at least at one temperature in the range in temperature from 218 Kelvin to 425 Kelvin to form transparent and ferromagnetic nanoparticles.

11. A semiconductor material comprising Mn-doped ZnO obtainable by the method according to claim 1 whereby said material comprises Mn-doped ZnO which has a Mn concentration not exceeding 5 at % atomic %, and which is ferromagnetic within at least a part of the temperature range from about 218 Kelvin to about 425 Kelvin,

2. A method for producing a ferromagnetic semiconductor material comprising Mn doped ZnO comprising the following steps:

providing a bulk material of Mn doped ZnO, and

creating a thin film on said bulk material by means of Pulsed Laser deposition at a maximum temperature of 600°

C. using said bulk material as target, whereby a thin film of Mn doped ZnO having a Mn concentration below 4 atomic % and which is ferromagnetic at least at one temperature in the range in temperature from 218 Kelvin to 425 Kelvin is obtained on said bulk material.

16. The method as recited in claim 2, further comprising the step of:

processing, by means of particle size selection, said Mn doped ZnO having a Mn concentration below 5 atomic % arid which is ferromagnetic at least at one temperature in the range in temperature from 218 Kelvin to 425 Kelvin to form transparent and ferromagnetic nanoparticles.

3. A method for producing a ferromagnetic semiconductor material comprising Mn doped ZnO comprising the following steps:

producing said material by sputtering to a deposition substrate, simultaneously using two metallic targets of Zinc and Manganese, respectively;

controlling the temperature on the deposition substrate to a maximum of 650°

C.; and

adjusting a sputtering energy on the Zinc and Manganese targets such that a resulting Manganese content in the 1-5 atomic % range is achieved, whereby Mn doped ZnO having a Mn concentration below 5 atomic % and which is ferromagnetic at least at one temperature in the range in temperature from 218 Kelvin to 425 Kelvin is obtained

4. A method for producing a ferromagnetic semiconductor material comprising Mn doped ZnO comprising the steps of:

producing said material by sputtering to a deposition substrate, using a sintered ZnO;

Mn ceramic target;

controlling the temperature on the deposition substrate to a maximum of 650°

C.; and

adjusting a sputtering energy on the target such that a resulting Manganese content in the 1-5 atomic % range is achieved, whereby Mn doped ZnO having a Mn concentration below 5 atomic % and which is ferromagnetic at least at one temperature in the range in temperature from 218 Kelvin to 425. Kelvin is obtained.

8. A ferromagnetic semiconductor material comprising Mn-doped ZnO wherein said Mn-doped ZnO has a Mn concentration not exceeding 5 at % atomic %, and is ferromagnetic within at least a part of the temperature range from about 218 Kelvin to about 425 Kelvin.

9. The material as recited in claim 8, further characterised in that it which is transparent.

10. The material as recited in claim 8 which is piezoelectric

12. A substrate having at least one thin layer deposited on at least one part of its surface, wherein said layer comprises a material according to claim 8.

13. A component to be used for electronic applications, wherein said component comprises a material according to claim 8.

14. A component to be used for spintronic applications, wherein said component comprises a material according to claim 8.

15. A. component to be used for optical applications, wherein said component comprises a material according to claim 8.

17. The material as recited in claim 9 which is piezoelectric

18. A substrate having at least one thin layer deposited on at least one part of its surface, wherein said layer comprises a material according to claim 9.

19. A component to be used for electronic applications, wherein said component comprises a material according to claim 9

20. A component to be used for spintronic applications, wherein said component comprises a material according to claim 9.