Phase separation and superparamagnetism in the martensitic phase of N i50-x C ox M n40 S n10

S. Yuan, P. L. Kuhns, A. P. Reyes, J. S. Brooks, M. J R Hoch, V. Srivastava, R. D. James, C. Leighton

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Ni50-xCoxMn40Sn10 shape memory alloys in the approximate range 5≤x≤8 display desirable properties for applications as well as intriguing magnetism. These off-stoichiometric Heusler alloys undergo a martensitic phase transformation at a temperature TM of 300-400 K, from ferromagnetic (FM) to nonferromagnetic, with unusually low thermal hysteresis and a large change in magnetization. The low temperature magnetic structures in the martensitic phase of such alloys, which are distinctly inhomogeneous, are of great interest but are not well understood. Our present use of spin echo nuclear magnetic resonance in the large hyperfine fields at Mn55 sites provides compelling evidence that nanoscale magnetic phase separation into FM and antiferromagnetic (AFM) regions occurs below TM in alloys with x in the range 0 to 7. At finite Co substitution, the FM regions are found to be of two distinct types, corresponding to high and low local concentrations of Co on Ni sites. Estimates of the size distributions of both the FM and AFM nanoregions have been made. At x=7, the AFM component is not long-range ordered, even below 4 K, and is quite different from the AFM component found at x=0; by x=14, the FM phase is completely dominant. Of particular interest, we find for x=7 that field cooling leads to dramatic changes in the AFM regions. These findings provide insight into the origins of magnetic phase separation and superparamagnetism in these complex alloys, particularly their intrinsic exchange bias, which is of considerable current interest.

Original languageEnglish (US)
Article number094425
JournalPhysical Review B
Volume93
Issue number9
DOIs
StatePublished - Mar 21 2016

Fingerprint

Superparamagnetism
Phase separation
Magnetic separation
Magnetic structure
Magnetism
shape memory alloys
Shape memory effect
phase transformations
Hysteresis
Magnetization
echoes
Substitution reactions
Phase transitions
hysteresis
Nuclear magnetic resonance
substitutes
Cooling
cooling
Temperature
magnetization

Cite this

Yuan, S., Kuhns, P. L., Reyes, A. P., Brooks, J. S., Hoch, M. J. R., Srivastava, V., ... Leighton, C. (2016). Phase separation and superparamagnetism in the martensitic phase of N i50-x C ox M n40 S n10. Physical Review B, 93(9), [094425]. https://doi.org/10.1103/PhysRevB.93.094425

Phase separation and superparamagnetism in the martensitic phase of N i50-x C ox M n40 S n10. / Yuan, S.; Kuhns, P. L.; Reyes, A. P.; Brooks, J. S.; Hoch, M. J R; Srivastava, V.; James, R. D.; Leighton, C.

In: Physical Review B, Vol. 93, No. 9, 094425, 21.03.2016.

Research output: Contribution to journalArticle

Yuan, S. ; Kuhns, P. L. ; Reyes, A. P. ; Brooks, J. S. ; Hoch, M. J R ; Srivastava, V. ; James, R. D. ; Leighton, C. / Phase separation and superparamagnetism in the martensitic phase of N i50-x C ox M n40 S n10. In: Physical Review B. 2016 ; Vol. 93, No. 9.
@article{72ed425bc99e4fad98778aa0fb270aea,
title = "Phase separation and superparamagnetism in the martensitic phase of N i50-x C ox M n40 S n10",
abstract = "Ni50-xCoxMn40Sn10 shape memory alloys in the approximate range 5≤x≤8 display desirable properties for applications as well as intriguing magnetism. These off-stoichiometric Heusler alloys undergo a martensitic phase transformation at a temperature TM of 300-400 K, from ferromagnetic (FM) to nonferromagnetic, with unusually low thermal hysteresis and a large change in magnetization. The low temperature magnetic structures in the martensitic phase of such alloys, which are distinctly inhomogeneous, are of great interest but are not well understood. Our present use of spin echo nuclear magnetic resonance in the large hyperfine fields at Mn55 sites provides compelling evidence that nanoscale magnetic phase separation into FM and antiferromagnetic (AFM) regions occurs below TM in alloys with x in the range 0 to 7. At finite Co substitution, the FM regions are found to be of two distinct types, corresponding to high and low local concentrations of Co on Ni sites. Estimates of the size distributions of both the FM and AFM nanoregions have been made. At x=7, the AFM component is not long-range ordered, even below 4 K, and is quite different from the AFM component found at x=0; by x=14, the FM phase is completely dominant. Of particular interest, we find for x=7 that field cooling leads to dramatic changes in the AFM regions. These findings provide insight into the origins of magnetic phase separation and superparamagnetism in these complex alloys, particularly their intrinsic exchange bias, which is of considerable current interest.",
author = "S. Yuan and Kuhns, {P. L.} and Reyes, {A. P.} and Brooks, {J. S.} and Hoch, {M. J R} and V. Srivastava and James, {R. D.} and C. Leighton",
year = "2016",
month = "3",
day = "21",
doi = "10.1103/PhysRevB.93.094425",
language = "English (US)",
volume = "93",
journal = "Physical Review B",
issn = "2469-9950",
publisher = "American Physical Society",
number = "9",

}

TY - JOUR

T1 - Phase separation and superparamagnetism in the martensitic phase of N i50-x C ox M n40 S n10

AU - Yuan, S.

AU - Kuhns, P. L.

AU - Reyes, A. P.

AU - Brooks, J. S.

AU - Hoch, M. J R

AU - Srivastava, V.

AU - James, R. D.

AU - Leighton, C.

PY - 2016/3/21

Y1 - 2016/3/21

N2 - Ni50-xCoxMn40Sn10 shape memory alloys in the approximate range 5≤x≤8 display desirable properties for applications as well as intriguing magnetism. These off-stoichiometric Heusler alloys undergo a martensitic phase transformation at a temperature TM of 300-400 K, from ferromagnetic (FM) to nonferromagnetic, with unusually low thermal hysteresis and a large change in magnetization. The low temperature magnetic structures in the martensitic phase of such alloys, which are distinctly inhomogeneous, are of great interest but are not well understood. Our present use of spin echo nuclear magnetic resonance in the large hyperfine fields at Mn55 sites provides compelling evidence that nanoscale magnetic phase separation into FM and antiferromagnetic (AFM) regions occurs below TM in alloys with x in the range 0 to 7. At finite Co substitution, the FM regions are found to be of two distinct types, corresponding to high and low local concentrations of Co on Ni sites. Estimates of the size distributions of both the FM and AFM nanoregions have been made. At x=7, the AFM component is not long-range ordered, even below 4 K, and is quite different from the AFM component found at x=0; by x=14, the FM phase is completely dominant. Of particular interest, we find for x=7 that field cooling leads to dramatic changes in the AFM regions. These findings provide insight into the origins of magnetic phase separation and superparamagnetism in these complex alloys, particularly their intrinsic exchange bias, which is of considerable current interest.

AB - Ni50-xCoxMn40Sn10 shape memory alloys in the approximate range 5≤x≤8 display desirable properties for applications as well as intriguing magnetism. These off-stoichiometric Heusler alloys undergo a martensitic phase transformation at a temperature TM of 300-400 K, from ferromagnetic (FM) to nonferromagnetic, with unusually low thermal hysteresis and a large change in magnetization. The low temperature magnetic structures in the martensitic phase of such alloys, which are distinctly inhomogeneous, are of great interest but are not well understood. Our present use of spin echo nuclear magnetic resonance in the large hyperfine fields at Mn55 sites provides compelling evidence that nanoscale magnetic phase separation into FM and antiferromagnetic (AFM) regions occurs below TM in alloys with x in the range 0 to 7. At finite Co substitution, the FM regions are found to be of two distinct types, corresponding to high and low local concentrations of Co on Ni sites. Estimates of the size distributions of both the FM and AFM nanoregions have been made. At x=7, the AFM component is not long-range ordered, even below 4 K, and is quite different from the AFM component found at x=0; by x=14, the FM phase is completely dominant. Of particular interest, we find for x=7 that field cooling leads to dramatic changes in the AFM regions. These findings provide insight into the origins of magnetic phase separation and superparamagnetism in these complex alloys, particularly their intrinsic exchange bias, which is of considerable current interest.

UR - http://www.scopus.com/inward/record.url?scp=84961875733&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84961875733&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.93.094425

DO - 10.1103/PhysRevB.93.094425

M3 - Article

AN - SCOPUS:84961875733

VL - 93

JO - Physical Review B

JF - Physical Review B

SN - 2469-9950

IS - 9

M1 - 094425

ER -