^{1}, K. G. Suresh

^{1,a)}and A. K. Nigam

^{2}

### Abstract

The first order austenite to martensitic transition in the off-stoichiometric Heusler alloy Ni–Co–Mn–Sb has been studied using magnetization, electrical resistivity, and heat capacitymeasurements with different field cooling protocols and thermal cyclings. The coexistence of high temperature, high magnetic austenite phase along with the low temperature and low magnetic martensitic phase after field cooling has been confirmed by all these measurements. The time dependence of these data quite vividly illustrates the metastability of the supercooled/superheated phase in the disorder-broadened first order transition.

I. INTRODUCTION

II. EXPERIMENTAL DETAILS

III. EXPERIMENTAL RESULTS

IV. DISCUSSION

V. CONCLUSIONS

### Key Topics

- Martensitic phase transitions
- 37.0
- Electrical resistivity
- 30.0
- Heat capacity
- 24.0
- Curie point
- 15.0
- Alloy phase transitions
- 13.0

## Figures

The x-ray diffraction patterns of along with the Rietveld refinement. The Rietveld refinement clearly shows the single phase of the sample.

The x-ray diffraction patterns of along with the Rietveld refinement. The Rietveld refinement clearly shows the single phase of the sample.

ZFC (closed circle) and FCW (open circle) magnetization in as a function of temperature in various fields. In the FCW case, the cooling and the measuring fields were the same.

ZFC (closed circle) and FCW (open circle) magnetization in as a function of temperature in various fields. In the FCW case, the cooling and the measuring fields were the same.

FCW curve measured in 20 kOe after field cooling in the same field and after waiting for different durations before starting the measurement. Inset shows the dependence of FCC magnetization on the cooling rate in . Data are taken with cooling rates of 0.4, 1, and 4 K/min in a field of 20 kOe.

FCW curve measured in 20 kOe after field cooling in the same field and after waiting for different durations before starting the measurement. Inset shows the dependence of FCC magnetization on the cooling rate in . Data are taken with cooling rates of 0.4, 1, and 4 K/min in a field of 20 kOe.

Temperature dependence of electrical resistivity in measured in different fields. The open circles represent the data taken in zero field (curve-1) and the star symbol represents the data taken in 80 kOe (curve-2), both after zero field cooling to 5 K. The triangles represent the data taken in zero field (curve-3), after field cooling in 80 kOe and squares represent the data taken in 80 kOe (curve-4), after field cooling in 80 kOe The inset shows the expanded view of the separation between curve-1 (circle) and curve-3 (triangle).

Temperature dependence of electrical resistivity in measured in different fields. The open circles represent the data taken in zero field (curve-1) and the star symbol represents the data taken in 80 kOe (curve-2), both after zero field cooling to 5 K. The triangles represent the data taken in zero field (curve-3), after field cooling in 80 kOe and squares represent the data taken in 80 kOe (curve-4), after field cooling in 80 kOe The inset shows the expanded view of the separation between curve-1 (circle) and curve-3 (triangle).

(a) Thermomagnetic measurements performed in in 1 kOe field in the low temperature region (where the difference between ZFC and FCW magnetization plots is considerable). The filled triangles show the normal ZFC data and the filled circles represent the ZFC data measured after thermal cycling. The open circles show the FCW data. (b) Temperature dependence of resistivity measured in zero field. The open circles represent the data taken in zero field, after zero field cooling. The closed circles represent the curve taken in zero field on thermal cycling after field cooling in 80 kOe. The triangles represent the normal FCW data with and , without thermal cycling.

(a) Thermomagnetic measurements performed in in 1 kOe field in the low temperature region (where the difference between ZFC and FCW magnetization plots is considerable). The filled triangles show the normal ZFC data and the filled circles represent the ZFC data measured after thermal cycling. The open circles show the FCW data. (b) Temperature dependence of resistivity measured in zero field. The open circles represent the data taken in zero field, after zero field cooling. The closed circles represent the curve taken in zero field on thermal cycling after field cooling in 80 kOe. The triangles represent the normal FCW data with and , without thermal cycling.

Magnetization isotherms and field dependence of resistivity in . (a) and (b) the sample was ZFC to 5 K and then heated back to 105 K. (c) and (d) after directly cooling to 105K (in zero field).

Magnetization isotherms and field dependence of resistivity in . (a) and (b) the sample was ZFC to 5 K and then heated back to 105 K. (c) and (d) after directly cooling to 105K (in zero field).

(a) Magnetization isotherms in measured at 5 K after field cooling the sample in different fields . The measuring field was applied in the sequence . The inset in figure (a) represents the shift in the magnetization loops to negative direction with increase in cooling field. (b) Field variation in resistivity at 5 K measured in the same sequence.

(a) Magnetization isotherms in measured at 5 K after field cooling the sample in different fields . The measuring field was applied in the sequence . The inset in figure (a) represents the shift in the magnetization loops to negative direction with increase in cooling field. (b) Field variation in resistivity at 5 K measured in the same sequence.

as a function of temperature, in measured in zero and in 50 kOe. The open circles represent the data taken in zero field and the star symbol represents the data taken in 50 kOe, both after zero field cooling to 2 K. The triangles represent the data taken in zero field and square represents the data taken in 50 kOe, both after field cooling in 50 kOe to 2 K. The inset highlights the separation of ZFC curves and field cooled curves. All the data are measured in the heating cycle.

as a function of temperature, in measured in zero and in 50 kOe. The open circles represent the data taken in zero field and the star symbol represents the data taken in 50 kOe, both after zero field cooling to 2 K. The triangles represent the data taken in zero field and square represents the data taken in 50 kOe, both after field cooling in 50 kOe to 2 K. The inset highlights the separation of ZFC curves and field cooled curves. All the data are measured in the heating cycle.

Time dependence of heat capacity measured in at 10 K. Prior to the measurement the sample was field cooled to 10 K in 60 kOe.

Time dependence of heat capacity measured in at 10 K. Prior to the measurement the sample was field cooled to 10 K in 60 kOe.

Magnetization relaxation in measured at 50 K after cooling from 200 K in different fields and then reducing the field to zero.

Magnetization relaxation in measured at 50 K after cooling from 200 K in different fields and then reducing the field to zero.

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