The mixed-valent Pb3Rh7O15 undergoes a Verwey-type transition at Tv≈180K, below which the development of Rh3＋3＋/Rh4＋4＋ charge order induces an abrupt conductor-to-insulator transition in resistivity. Here we inve...The mixed-valent Pb3Rh7O15 undergoes a Verwey-type transition at Tv≈180K, below which the development of Rh3＋3＋/Rh4＋4＋ charge order induces an abrupt conductor-to-insulator transition in resistivity. Here we investigate the effect of pressure on the Verwey-type transition of Pb3Rh7O15 by measuring its electrical resistivity under hydrostatic pressures up to 8GPa with a cubic anvil cell apparatus. We find that the application of high pressure can suppress the Verwey-type transition around 3GPa, above which a metallic state is realized at temperatures below ～70K, suggesting the melting of charge order by pressure. Interestingly, the low-temperature metallic region shrinks gradually upon further increasing pressure and disappears completely at P〉7GPa, which indicates that the charge carriers in Pb3Rh7O15 undergo a reentrant localization under higher pressures. We have constructed a temperature-pressure phase diagram for Pb3Rh7O15 and compared to that of Fe3O4, showing an archetype Verwey transition.展开更多
Structure model of charge-ordered La_0.33 Ca_0.67 MnO_3, perovskite is one of current focused study in condensed matter physics. There are great discrepancies in previous studies in this field. Our transmission electr...Structure model of charge-ordered La_0.33 Ca_0.67 MnO_3, perovskite is one of current focused study in condensed matter physics. There are great discrepancies in previous studies in this field. Our transmission electron microscopy study confirms Wigner crystal model with transverse displacement and is not consisent with the hi-stripe model with longitudinal displacement. We observed incommensurate modulation and anti-phase domains with a displacement vector a_co/3 in charge--ordered La_0.33 Ca_0.67 MnO_3, perovskite.展开更多
Cooling and heating modes are shown to be able to significantly modify the magnetic and electrical properties of the half-doped perovskite manganite.The present paper reports on a precise investigation of this phenome...Cooling and heating modes are shown to be able to significantly modify the magnetic and electrical properties of the half-doped perovskite manganite.The present paper reports on a precise investigation of this phenomenon(the so-called training effect) carried out on Nd0.5Ca0.5MnO3 manganite,which allow a fine tuning of the magnetic ground state.Refinement of the X-ray diffraction pattern shows that the synthesized sample is single phase and crystallizes in the orthorhombic structure with Pnma space group.Using magnetometry measurements,we have found that the sample is the seat of interesting phenomena like charge ordering,magnetic phase separation,spin-glass and inverse magnetocaloric effect.Magnetic-field-driven magnetization(M(μ0 H)) measurements evidence the metamagnetic transition which not only depends on field value,but also on the thermal process(cooling or heating).Metamagnetic irreversibility in the magnetic field range(±5 T) and memory effect are observed at low temperatures due to the kinetic arrest phenomenon.It is worthwhile to mention that the coercive field increases with decreasing temperature and reaches 955 Oe at 20 K,which is sufficiently large compared with that one in the soft magnetic and makes the material quite interesting for spintronic applications.The electrical resistivity in a zero field was measured on both cooling and warming modes,and the data obtained were fitted by using different theoretical models.At low temperatures,the resistivity shows the presence of insulator-metal transition and is found to be in conformity with the magnetization data.A magnetic training effect due to the thermo-magnetic history dependent behavior is observed,where the resistivity is consistently irreversible.展开更多
基金Supported by the"Shi-Pei Ji Hua",the National Science Foundation of China under Grant Nos 51402019 and 11574377the Beijing Natural Science Foundation under Grant No 2152011+5 种基金the National Basic Research Program of China under Grants No2014CB921500the Strategic Priority Research ProgramKey Research Program of Frontier Sciences of the Chinese Academy of Sciences under Grant Nos XDB07020100 and QYZDB-SSW-SLH013the U.S.Department of Energy,Office of Science,Basic Energy Sciences,Materials Sciences and Engineering Divisionthe CEMNSF MRSEC under Grant No DMR-1420451
文摘The mixed-valent Pb3Rh7O15 undergoes a Verwey-type transition at Tv≈180K, below which the development of Rh3＋3＋/Rh4＋4＋ charge order induces an abrupt conductor-to-insulator transition in resistivity. Here we investigate the effect of pressure on the Verwey-type transition of Pb3Rh7O15 by measuring its electrical resistivity under hydrostatic pressures up to 8GPa with a cubic anvil cell apparatus. We find that the application of high pressure can suppress the Verwey-type transition around 3GPa, above which a metallic state is realized at temperatures below ～70K, suggesting the melting of charge order by pressure. Interestingly, the low-temperature metallic region shrinks gradually upon further increasing pressure and disappears completely at P〉7GPa, which indicates that the charge carriers in Pb3Rh7O15 undergo a reentrant localization under higher pressures. We have constructed a temperature-pressure phase diagram for Pb3Rh7O15 and compared to that of Fe3O4, showing an archetype Verwey transition.
文摘Structure model of charge-ordered La_0.33 Ca_0.67 MnO_3, perovskite is one of current focused study in condensed matter physics. There are great discrepancies in previous studies in this field. Our transmission electron microscopy study confirms Wigner crystal model with transverse displacement and is not consisent with the hi-stripe model with longitudinal displacement. We observed incommensurate modulation and anti-phase domains with a displacement vector a_co/3 in charge--ordered La_0.33 Ca_0.67 MnO_3, perovskite.
文摘Cooling and heating modes are shown to be able to significantly modify the magnetic and electrical properties of the half-doped perovskite manganite.The present paper reports on a precise investigation of this phenomenon(the so-called training effect) carried out on Nd0.5Ca0.5MnO3 manganite,which allow a fine tuning of the magnetic ground state.Refinement of the X-ray diffraction pattern shows that the synthesized sample is single phase and crystallizes in the orthorhombic structure with Pnma space group.Using magnetometry measurements,we have found that the sample is the seat of interesting phenomena like charge ordering,magnetic phase separation,spin-glass and inverse magnetocaloric effect.Magnetic-field-driven magnetization(M(μ0 H)) measurements evidence the metamagnetic transition which not only depends on field value,but also on the thermal process(cooling or heating).Metamagnetic irreversibility in the magnetic field range(±5 T) and memory effect are observed at low temperatures due to the kinetic arrest phenomenon.It is worthwhile to mention that the coercive field increases with decreasing temperature and reaches 955 Oe at 20 K,which is sufficiently large compared with that one in the soft magnetic and makes the material quite interesting for spintronic applications.The electrical resistivity in a zero field was measured on both cooling and warming modes,and the data obtained were fitted by using different theoretical models.At low temperatures,the resistivity shows the presence of insulator-metal transition and is found to be in conformity with the magnetization data.A magnetic training effect due to the thermo-magnetic history dependent behavior is observed,where the resistivity is consistently irreversible.
