Very few materials show large magnetoresistance(MR)under a low magnetic field at room temperature,which causes the barrier to the development of magnetic field sensors for detecting low-level electromagnetic radiation...Very few materials show large magnetoresistance(MR)under a low magnetic field at room temperature,which causes the barrier to the development of magnetic field sensors for detecting low-level electromagnetic radiation in real-time.Here,a hybrid reduced graphene oxide(rGO)-based magnetic field sensor is produced by in situ deposition of FeCo nanoparticles(NPs)on reduced graphene oxide(rGO).Special quantum magnetoresistance(MR)of the hybrid rGO is observed,which unveils that Abrikosov's quantum model for layered materials can occur in hybrid rGO;meanwhile,the MR value can be tunable by adjusting the particle density of FeCo NPs on rGO nanosheets.Very high MR value up to 21.02±5.74%at 10 kOe at room temperature is achieved,and the average increasing rate of resistance per kOe is up to 0.9282ΩkOe^-1.In this paper,we demonstrate that the hybrid rGO-based magnetic field sensor can be embedded in a wireless system for real-time detection of low-level electromagnetic radiation caused by a working mobile phone.We believe that the two-dimensional nanomaterials with controllable MR can be integrated with a wireless system for the future connected society.展开更多
In this paper,the giant magnetoresistance(GMR)multilayer sensor is fabricated with a Wheatstone bridge,and it exhibits excellent performance with a sensitivity of 2.8349 mV/(V/Oe)(1 Oe=79.5775 A·m^-1)and a satura...In this paper,the giant magnetoresistance(GMR)multilayer sensor is fabricated with a Wheatstone bridge,and it exhibits excellent performance with a sensitivity of 2.8349 mV/(V/Oe)(1 Oe=79.5775 A·m^-1)and a saturation field of 26 Oe along the sensitive axis.The GMR sensor is also characterized in a high magnetic field.The sensitivity decreases from 2.8349 mV/(V/Oe)at an angle of 0°to 0.0175 mV/(V/Oe)at an angle of 90°.Then,the sensor is placed in a series of rotating magnetic fields.We propose a model to express the output characteristics of the GMR multilayer sensor.The transfer curves of the sensor can be shown as two exactly symmetrical circles with an increasing radius when the magnetic field increases.The experimental results are consistent with the simulation results of the model.The advantage of this model is that it is simpler and more intuitive.展开更多
Magnetic sensors based on tunneling magnetoresistance(TMR)effect exhibit high sensitivity,small size,and low power consumption.They have gained a lot of attention and have potential applications in various domains.Thi...Magnetic sensors based on tunneling magnetoresistance(TMR)effect exhibit high sensitivity,small size,and low power consumption.They have gained a lot of attention and have potential applications in various domains.This study first introduces the development history and basic principles of TMR sensors.Then,a comprehensive description of TMR sensors linearization and Wheatstone bridge configuration is presented.Two key performance parameters,the field sensitivity and noise mechanisms,are considered.Finally,the emerging applications of TMR sensors are discussed.展开更多
The anisotropic magnetoresistance film is an important core material for developing the magnetic sensors.Here,Ta(5)/Mg O(3)/Ni Fe(10)/Mg O(3)/Ta(3)multilayers(in nanometer)were prepared by magnetron sputtering and fur...The anisotropic magnetoresistance film is an important core material for developing the magnetic sensors.Here,Ta(5)/Mg O(3)/Ni Fe(10)/Mg O(3)/Ta(3)multilayers(in nanometer)were prepared by magnetron sputtering and further applied to construct a sensor element by combining with the Wheatstone bridge.The 1/f noise of the sensor element was greatly reduced by three orders of magnitude after annealing at 400℃for 7200 s,which was mainly due to the significant microstructural changes during the annealing.However,when the sensor element was applied to detect the magnetic signal of a magnetic code disk with 512 N-S magnetic poles,the output voltage signal of the sensor displayed a large fluctuation of±0.05 V.In order to reduce the voltage fluctuation,a magnetic sensor chip by using a parallelly arranged multipath Wheatstone bridges and auto-gain compensation structure was designed,and magnetic sensor elements and the high-performance computing drive module were prepared.The output voltage fluctuation of the magnetic sensor was reduced by about 90%and approached to±0.005 V.These findings provide an important basis for the practical application of Ni Fe-based magnetic sensing film materials.展开更多
Magnetic tunnel junctions （MTJs）, as the seminal spintronic devices, are expected for applications in magne- toresistive sensors due to their large magnetoresistance （MR） and high field sensitivity. Two hybrid Co/...Magnetic tunnel junctions （MTJs）, as the seminal spintronic devices, are expected for applications in magne- toresistive sensors due to their large magnetoresistance （MR） and high field sensitivity. Two hybrid Co/insulator/ZnO：Co junctions were fabricated with two different barriers to investigate the magneto-transport properties. Experimental results indicate that, both Co/MgO/ZnO：Co and Co/ZnO/ZnO：Co junctions show the positive and nearly linear MR, and their tunnel magnetoresistances （TMR） are 21.8% and 13.6%, respectively, when the current is applied perpendicular to the film plane under the magnetic field of 2 T at 4 K. The nonlinearity of MR is less than 1% within the magnetic field （H） of 1 kOe 〈 H 〈 12 kOe at low temperature, making them attractive as magnetoresistive sensors. The higher MR of Co/MgO/ZnO：Co junctions is due to the superior spin filtering effect and larger effective barrier height of the MgO barrier. This linear MR characteristic of Co/insulator/ZnO：Co structures shows a promising future on the applications of diluted magnetic semiconductors in magnetoresistive sensors.展开更多
基金the financial support from Canada Innovation Fund-Leaders Opportunity Fundthe Natural Sciences and Engineering Research Council of Canada(NSERC).
文摘Very few materials show large magnetoresistance(MR)under a low magnetic field at room temperature,which causes the barrier to the development of magnetic field sensors for detecting low-level electromagnetic radiation in real-time.Here,a hybrid reduced graphene oxide(rGO)-based magnetic field sensor is produced by in situ deposition of FeCo nanoparticles(NPs)on reduced graphene oxide(rGO).Special quantum magnetoresistance(MR)of the hybrid rGO is observed,which unveils that Abrikosov's quantum model for layered materials can occur in hybrid rGO;meanwhile,the MR value can be tunable by adjusting the particle density of FeCo NPs on rGO nanosheets.Very high MR value up to 21.02±5.74%at 10 kOe at room temperature is achieved,and the average increasing rate of resistance per kOe is up to 0.9282ΩkOe^-1.In this paper,we demonstrate that the hybrid rGO-based magnetic field sensor can be embedded in a wireless system for real-time detection of low-level electromagnetic radiation caused by a working mobile phone.We believe that the two-dimensional nanomaterials with controllable MR can be integrated with a wireless system for the future connected society.
基金Project supported by the National Key Research and Development Program of China(Grant No.2018YFF01010701)the Natural Science Foundation of Zhejiang Province,China(Grant No.LQ17F010004)the National Natural Science Foundation of China(Grant No.61741506)
文摘In this paper,the giant magnetoresistance(GMR)multilayer sensor is fabricated with a Wheatstone bridge,and it exhibits excellent performance with a sensitivity of 2.8349 mV/(V/Oe)(1 Oe=79.5775 A·m^-1)and a saturation field of 26 Oe along the sensitive axis.The GMR sensor is also characterized in a high magnetic field.The sensitivity decreases from 2.8349 mV/(V/Oe)at an angle of 0°to 0.0175 mV/(V/Oe)at an angle of 90°.Then,the sensor is placed in a series of rotating magnetic fields.We propose a model to express the output characteristics of the GMR multilayer sensor.The transfer curves of the sensor can be shown as two exactly symmetrical circles with an increasing radius when the magnetic field increases.The experimental results are consistent with the simulation results of the model.The advantage of this model is that it is simpler and more intuitive.
基金financially supported by Beijing Municipal Science and Technology Project(No.Z201100004220002)the International Collaboration Project B16001+1 种基金the Key Research and Development Program of Shandong Province of China(No.2020S020201-01621)the Magnetic Sensor Innovation Platform from Laoshan District。
文摘Magnetic sensors based on tunneling magnetoresistance(TMR)effect exhibit high sensitivity,small size,and low power consumption.They have gained a lot of attention and have potential applications in various domains.This study first introduces the development history and basic principles of TMR sensors.Then,a comprehensive description of TMR sensors linearization and Wheatstone bridge configuration is presented.Two key performance parameters,the field sensitivity and noise mechanisms,are considered.Finally,the emerging applications of TMR sensors are discussed.
基金financially supported by the National Key Research and Development Program of China(Nos.2019YFB2005800 and 2019YFB1309902)the National Science Foundation of China(Nos.51871017 and 51871018)+3 种基金Beijing Natural Science Foundation(No.2192031)the Science and Technology Innovation Team Program of Foshan(No.FSOAA-KJ919-44020087)the Fundamental Research Funds for the Central Universities(No.FRF-TP-19-011B1)the Foundation of Beijing Key Laboratory of Metallic Materials and Processing for Modern Transportation。
文摘The anisotropic magnetoresistance film is an important core material for developing the magnetic sensors.Here,Ta(5)/Mg O(3)/Ni Fe(10)/Mg O(3)/Ta(3)multilayers(in nanometer)were prepared by magnetron sputtering and further applied to construct a sensor element by combining with the Wheatstone bridge.The 1/f noise of the sensor element was greatly reduced by three orders of magnitude after annealing at 400℃for 7200 s,which was mainly due to the significant microstructural changes during the annealing.However,when the sensor element was applied to detect the magnetic signal of a magnetic code disk with 512 N-S magnetic poles,the output voltage signal of the sensor displayed a large fluctuation of±0.05 V.In order to reduce the voltage fluctuation,a magnetic sensor chip by using a parallelly arranged multipath Wheatstone bridges and auto-gain compensation structure was designed,and magnetic sensor elements and the high-performance computing drive module were prepared.The output voltage fluctuation of the magnetic sensor was reduced by about 90%and approached to±0.005 V.These findings provide an important basis for the practical application of Ni Fe-based magnetic sensing film materials.
基金supports by the National Natural Science Foundation of China (Nos.51202125 and 51231004)the National Basic Research Program of China (No. 2010CB832905)
文摘Magnetic tunnel junctions （MTJs）, as the seminal spintronic devices, are expected for applications in magne- toresistive sensors due to their large magnetoresistance （MR） and high field sensitivity. Two hybrid Co/insulator/ZnO：Co junctions were fabricated with two different barriers to investigate the magneto-transport properties. Experimental results indicate that, both Co/MgO/ZnO：Co and Co/ZnO/ZnO：Co junctions show the positive and nearly linear MR, and their tunnel magnetoresistances （TMR） are 21.8% and 13.6%, respectively, when the current is applied perpendicular to the film plane under the magnetic field of 2 T at 4 K. The nonlinearity of MR is less than 1% within the magnetic field （H） of 1 kOe 〈 H 〈 12 kOe at low temperature, making them attractive as magnetoresistive sensors. The higher MR of Co/MgO/ZnO：Co junctions is due to the superior spin filtering effect and larger effective barrier height of the MgO barrier. This linear MR characteristic of Co/insulator/ZnO：Co structures shows a promising future on the applications of diluted magnetic semiconductors in magnetoresistive sensors.
